How stable is the 820? Is it a worthwhile upgrade from the 520?

I switched from a 810 to a 820, I still have my 810 "just in case", I hadn't been experiencing the problems with the 810 that some others have (crashing etc).
In general the 820 has been an improvement, the sensitive touchscreen took time to get used to, the uploading is much better than the 810 and some of the IQ data fields are handy.
The biggest problem for me at the moment is the way it records elevation and the fact that both of the 820's I've had so far (original and Garmin replacement) record about 5% less total ascent on the same climbs as my 810.
Hopefully it'll be sorted soon in a firmware update. :(

The 810 has a resistive screen which needs quite a positive touch to register an input, the 820 has a capacitive screen (like a modern smartphone) that can be operated by barely touching the screen at all.
Reading on here it appears that some people have more trouble with the new screen than others.
The other problem with the capacitive screen is that it can be affected by drops of water or sweat causing the screens and data fields to change, this isn't a new problem, the Edge 1000 is affected as well.
The problem is easily solved by locking the screen and using an Edge Remote (something I've used with the 810 for quite a while).

I know spare time can be in short supply but have you scanned this forum, there are over 200 threads with thousands of posts and at least half cataloging problems including two large threads with 67 & 45 replies relating to "sensitive" touch screens. If I was going to buy a 820 (I was, but on hold) I would do some research by scanning at least the bigger threads which likely cover the most common problems.

I switched from 520 to 820.

It was worth it to me. The navigation alone was worth it. Create a course on Garmin connect, send to device, true turn by turn, much
easier, and more reliable then the previous methods I used to place a route on 520.

Yes, I waited for a few sw updates to be released. Had no issues with screen sensitivity or WiFi.

Also the 520 still has value to sell used, helps defray purchase price.

I know spare time can be in short supply but have you scanned this forum, there are over 200 threads with thousands of posts and at least half cataloging problems including two large threads with 67 & 45 replies relating to "sensitive" touch screens. If I was going to buy a 820 (I was, but on hold) I would do some research by scanning at least the bigger threads which likely cover the most common problems.

If you take the time to read these threads you'll find, as usual, that a lot of the comments are made by a small handful of members with a bee in their bonnet about one problem or other, people who don't find it a problem don't usually take the time to comment.

If you take the time to read these threads you'll find, as usual, that a lot of the comments are made by a small handful of members with a bee in their bonnet about one problem or other, people who don't find it a problem don't usually take the time to comment.

First thing i would ask is do you have an 820 and do all its features work correctly ie elevation.

I have the 820 and it is my first garmin cycle computer(have used polar for the last 25+ years), personally I think it is a great bit of kit, looks great, does evertything its supposed to do except for one thing, Elevation is out by -50m aprox.
Its not a major issue to me once it gets fixed but it certainly makes me wonder how a company like Garmin can get this simple feature wrong !!!

There are many factual problems with the way the 820 functions. There is no question about that. Whether any of them are a significant problem for a particular user depends on how they use the unit and what they expect. For example, there are very significant issues with elevation and gradient. It's not something that much concerns me, but it is an important function and one that concerns many other users who have reasonable expectations as to how well it should function.

First thing i would ask is do you have an 820 and do all its features work correctly ie elevation.

I've had an 820 since the day after it was released, I'm currently on my second as Garmin wanted to "test" my first, the elevation problems have been consistent across the two.
The main problem, as far as I'm concerned is the fact that Total Ascent is approximately 5% less than my Edge 810, but Garmin will probably argue that this is within the margin for error for the devices.

Really surprised anyone would defend Garmin's handling of the buggy 820 at this point, TBH.

I'm just glad I hadn't sold my 520 yet, which made it easier to revert back when my 820 hardware proved to be unreliable.

If someone was looking at buying an 820, I'd advise them to stay far away, or at least buy from a dealer with a hassle-free, no-questions-asked return policy.

Really surprised anyone would defend Garmin's handling of the buggy 820 at this point, TBH.

As a long time user of Garmin products I'm used to waiting for firmware updates to rectify bugs, none of the bugs I've encountered are major issues as far as I'm concerned and the 820 already out performs my 810 in most respects.