Watch out for? No idea. It’s a watch and a great one. Decide if you want AppleCare not. You have 60 days. Personally I get it but I’m hard on my devices and like the peace of mind.
Tips: play with it. There are a ton of cool features. Not all may be useful to you. Every now and then I search google or YouTube for tips and tricks and usually end up finding something I didn’t know, or getting reminded of a feature I had forgotten. For example, did you know you can use your Apple Watch as a remote control for your phone when taking pictures or videos? That’s one I had forgotten about but can be quite useful to me.
I’m becoming a fan of the double tap feature. At first I didn’t think I’d use it but it’s quite handy in a few situations for me. You can pause or skip music, pause timers, automatically open up a reply to a text and use voice to text, plus a bunch of other stuff.
Watch faces? That’s gonna be up to you. I use several
I traded in my S6 for the Ultra 2 about a month and a half ago. I agree with everything u/SakuraSiri said. Yes, you are aware of the size the first couple days, but I quickly got used to it. I purchased mine with the Ocean band which is surprisingly way more comfortable than I expected. I bought some knock off trail loops on Amazon that are my day to day bands though.
I do like the brightness, a lot. On the flip side, the watch will dim down to 1 nit in low light situations and sometimes that makes it hard to see. That’s not a deal breaker to me but it is annoying at times.
A lot of the upgrades I’m really loving are also available on the S9, but not all. Day to day, the watch is much more responsive with the new chip. Siri is smoother - I use it a lot in conjunction with my reminders list, calendar, texting, etc. I also use my watch as a remote for Apple TV and interfacing with my burgeoning smart home via Apple Home. At work, quite often I leave my phone in the office and just use my watch and AirPods for phone calls, etc.
I had the opportunity to play with waypoints and the trackback feature the other day out in the woods. Man that’s handy. As a water enthusiast, I’m looking forward to using the watch on my boating trips but that will have to wait until the weather warms up.
I love the durability. I don’t worry about a case or screen protector. Havent’s scratched the watch yet - but I’ve scratched other things with it. Oops.
One thing I haven’t messed with is the workouts and fitness aspect. I really should I guess, but I don’t work out like I should. I bought it more for my outdoor adventures, health monitoring, integration into the Apple ecosystem… and let’s be honest, just because I like it and wanted it over the S6 or even the S9.
Bottom line, 10/10 would upgrade again.