Considering buying Vivoactive 3 from Fitbit Blaze/Versa. Thoughts?

There is definitely a lot of negative posts here on the Vivoactive 3 and with good reasons on many fronts!
Personally I think the VA3 is still a good device IF you get it with your eyes open and know of the issues and they are not deal breakers for you now, certainly don't buy expecting Garmin to fix them.

First up yes the size specs are accurate and I also think it looks good on smaller wrists unlike quite a few sport watches, also the standard replaceable strap it nice (just don't loose the lugs).

As you already know Garmin over promised on the battery and you won't get their claimed life on either normal usage or GPS active time, with the later being an issue if you do Ultras etc (although you can charge while an activity is recording), again from a personal point of view I usually charge it while in the shower and with 1-2 GPS activities a day I have never flattered it.

With activities know the limitations of the optical heart rate monitor (comes up a bit but being a Fitbit user you probably know of them already), expect the altitude from the barometer to be off, although calibration does help and although I have not had any issues with my town and trail running some have complained of GPS drift, again I can't comment as it has not happened to me.
Something else I cannot comment on is connected devices drop out which seems to be a BIG issue on the forum especially with the cyclists so if you are thinking of using it with a power meter etc definitely get some feedback from other users.

As for apps have a look at apps.garmin.com for the watch apps available (note there is a limited number you can have on the watch at the same time) and finally have a look at this post regarding transfering your Fitbit data, it's from 2016 so double check if you can still do it.
https://www.dcrainmaker.com/2016/11/garmin-enables-migration-from-fitbit-heres-how-it-works.html

Hopefully some of that helps, if I missed anything I am sure others will chime in.

It all really depends on your needs and expectations. It is not a Garmin premium watch, so if you think about it as a cheaper replacement for Fenix 5 you will be strongly disappointed. If you just look for a bit more advanced sport band you should be delighted with the features and the design.
Some key points worth to consider in my opinion:
- Battery life is more 4 days according to my experience - assuming ~2hrs of GPS, battery saving watch face, OHRM on, notifications on
- GPS and altimeter are not very accurate but I believe good enough for casual users
- Accept the fact that OHRM is good for all day static monitoring (sitting, sleeping, walking) but useless for most workouts (gym based, intervals, running). If you need accurate readings buy chest HRM, but make sure that you get the one which works with VA3 (see other threads)
- Make sure that your phone connects to VA3 without issues (see other threads) e.g. I had problems with Samsung Galaxy S5 but it works perfectly with LG V35

I'm personally happy with the device and the number of features it offers. I love the design of the slate version I have, especially after I replaced the original strap with the steel one. It is really slim comparing to other Garmin devices. However I would probably not buy it again and go with Fenix 5 due to the following reasons:
- I'm a runner, touch screen / side swipe are not good solution for cold / wet weather
- I would expect stronger battery
- I would expect less bugs and better support

As far as available apps for the va3, here's where to look:

https://apps.garmin.com/en-US/devices/vivoactive3/apps

As far as multitask, it not like you can run 2 widgets or watchapps at a time, but it does allow for background processes, where a widget can have a background that collects data every 5 minutes, and that info is available when you look at the widget.

Hi all, thanks for the replies. It sounds like none of the things Sciber or pieras123 mentioned are real deal breakers for me. Perhaps, due to the pedigree of Garmin typical Garmin users have very high expectations. And of course more serious athletes will have very strict requirements for accuracy, but as a casual user this sounds alright to me. Certainly GPS was never extremely accurate on the Fitbit, and likewise the heart rate sensor and altimeter. 5ish day battery life is okay for me as the Fitbits I used have similar if not lesser. Plus, I'm not a very heavy user so I may get more out of it. Anyway, always on display and STILL 5ish days gets no complaints from me.

And lastly, I really don't care for onboard music storage so the VA3M doesn't appeal to me, especially if it is the same device otherwise. If it is an upgraded device then may be. Otherwise I can get the VA3 cheaper now.

Hi litetaker. If you change the Fitbit to Garmin, it should be noted that automatic registration of daily activities, which is habitual for Fitbit, is absent by VA3. That is, Garmin began to make such a function in his own - called moveIQ, But it really does not work yet. (Or I do not know how to use it?)
Therefore, if you do not start each activity manually, in the evening you only have your steps, floors (30-50% of the amount counted by fitbit) and the pulse line.
And about the battery ... I charge my VA3 every third day, if I use GPS a hour per day. Those, of course, on the third day remain about 20% at evening, but this is not the amount that is enough for the fourth day.
Some visitors of the forum write that this problem (high battery drain) has come with FW 3.50 (i have VA3 only 4 weeks) so I hope that this problem will be solved in the next 2 weeks - the support promise a new FW.

Indeed, if I compare VA3 with Fitbit Blaze (the comparision that I can do) - Garmin wins hands down. Well, perhaps as global_local noted with exception of MoveIQ and somewhat - sleep detection. It is there, yet it works so badly (turns on/off for no apparent reason) that I disable it and forgot it does exists. But if you looking for things that Garmin promised for this device - wait, read, think and most likely look somewhere else.

All_toss I am not sure what you are referring to when you say it works so badly. Is is the sleep tracking or the MoveIQ? As long as MoveIQ can detect that I walked I am ok. I am not a serious athlete or even a very serious fitness enthusiast. I use it to enhance my everyday activities and my gym exercises. Is the MoveIQ good enough to at least track daily walks reliably?

One thing I seem to have noticed as I go through these forums is that a lot of users are very squarely in the serious athlete category. Things that would be minor inconveniences for me are treated as major disasters by some users (not to make light of their issues) and I can see why if I cared so much for precision. One example is GPS accuracy. For me, as long as the GPS error is within a margin of 5-10% I am ok with it. I come from Fitbit for pete sake! But it looks like for others if the GPS accuracy is off by even 1%, this is unacceptable. Likewise, I see some users complain about altimeter. But, firstly I know for a fact that altimeters that use pressure cannot be relied on. They depend on weather conditions and one day it may read 10 meters at a location, then the next day it will say 50 meters or -30 meters. That does not mean it is faulty. That is working as designed. I've also never bothered to really get into too much detail on that anyway. But for others this seems unacceptable. And I will never use a connected device like an external HR monitor either, not that hard core. Plus, I am more than satisfied with inaccuracies in HR readings, as long as I get the trends. I am mostly focused on my resting HR.

Hence, I am having to take this expectation mis-match into account when I process the perceived faults of the device. Plus after seeing more video reviews, I am very excited about a lot of things this device can do. I can see a lot more detailed data on the device itself, I can use a lot of widgets/data fields to show so much more data during activities and after. And one thing I am impressed by is just how snappy the device feels in reviews compared to my (now returned back to Amazon) Fitbit Versa. I was hugely disappointed when I went from the Fitbit Blaze to Versa. On the Blaze, every function and feature on the device was snappy. I could go into the "Exercise" function immediately, and start an activity. On the Versa (and presumably Ionic, as they have the same software) each feature is now a full blown app. And boy are these apps SLOW! It takes almost 2 seconds to load the app. Then I can start the activity which also feels slow. And when compared to the 0.25 seconds to 0.5 seconds it takes on the Blaze this was very annoying. On the Garmin, everything seemed to load up immediately! No real waiting. I have not seen too many videos of actual third party apps running on this but I saw some running on the Fenix. And if the Fenix has similar processing capabilities as this then I am happy that there is literally no load time for launching third party apps too!

Plus I love that you can customize the watch face and seemingly have multiple watch faces loaded on the device so that you can switch them at will without needing to pair with the phone. Oh boy, that is another indignity of the Fitbit Versa.

Long story short, I bit the bullet and bought the VA3 on Amazon! :D Super excited to be joining the Garmin world! :)

Little follow up as I completely forgot about MoveIQ and it has been brought up by Fitbit users on here as Fitbits are supposed to be excellent at auto detecting your activities and recording and categorizing them for you.
MoveIQ is not so great, when I first got my VA3 and was trying the features I did experiment with it but it would regularly detect things like riding a motorcycle as cycling (those burned some calories) and when it recorded runs for example it could take 5-10mins to detect and if I was slowly jogging up a hill it might auto pause.
Personally it was not a feature I wanted anyway as I prefer more granular control of recording and to start and activity you just press the button and tap the activity you want so it's not a /slowhard thing to do.

Looks like you know about the inaccuracies of the Altimeter technology, one thing to note is when you start and activity it pulls your initial height from the GPS (or you can enter it manually) so it can be quite accurate to start with but as time progresses it will drift and other factors such as humidity/temperature change and sweat blocking the input will accelerate this.

On the app front they can be quite snappy when programmed well although you will notice delays on any that pull data through your phone.
As I mentioned there is a limitation on how many downloaded apps/widgets/Datafields/Watch Faces you can have loaded on the watch as once, I am maxed at 16 with 3 being watch faces which I change depending on mood.

In the end I hope you like the VA3 when you get it.

when it recorded runs for example it could take 5-10mins to detect

Do you realize this is by design? You have to go into Garmin Connect and set how long you run before Move IQ starts recording it as an activity.