I got my Instinct yesterday, and thought I might post some of my first impressions. I've had a number of Garmin watches, including the Forerunner 210 and every fenix from the 2 through the 5X Plus. I really like the Instinct, and here are a few reasons why.
1. It was smaller than I expected. Very much Casio-watch sized.
2. Screen contrast is excellent. In low light, the screen is far more visible than the fenix 5X. In daylight, it sometimes feels like the backlight is on because the screen reflects so much ambient light.
3. The inset circle display is really well executed. It would be easy for it to be a gimmick, but Garmin has done a really good job utilizing it. For example, it provides an actually useful 4th data field on the 3-field layout that you'd be familiar with from the fenix. It's also used to display a progress bar and status icons on various screens and as a selection indicator on the controls menu or the on-screen keyboard (which is circular here instead of vertical as it is on the fenix line)
4. The screen is low resolution but the watch is extremely responsive and there are lots of subtle animations that make it feel like a modern watch rather than an old-school LCD.
5. The default hot-key configuration is extremely thoughtful and very well presented. Long-pressing the start button, for example, shows you the current GPS coordinates and allows you to save your current location. You could set this up on a fenix but there is some extra UI here that I haven't seen before. Long pressing the back button (SET) takes you to a sub-menu where you can set time with GPS and use the stopwatch and timer. The countdown timer also now has a memory of different values, which I haven't seen before. Long pressing the down button (ABC) takes you to a version of the altimeter-barometer-compass widget. Again, you could set this up on the fenix but the UI is slightly different here and feels more cohesive.
6. The vibration motor is really powerful.
The overall impression I've come away with is that the Outdoor group at Garmin has really put a lot of time and effort into creating a watch that in a lot of ways feels more tightly integrated than the fenix line. Yes, it has less functionality, but the functionality that it has is presented in a less confusing and more intuitive way.