One thing that I have found about the Apple Watch is that there are a million things that it can do, but most people are going to try to use just a handful of them. The features that you do use most people will love and come to rely on.
For me it is messages first. I absolutely love getting and sending messages via the watch. It really works the way messages should be. Short and right to the point. Now with the newest update, you can send many more types of cute messages making it that much better.
The activity tracker is also something that I rely on. I love counting my step and getting that reminder to "stand-up" every hour if I don't. When I go for a run or hike, I can track my progress easily and very clearly.
I think that the battery is also very good. I charge it next to my bed every night and it usually has about 40% left. There have been a few days that I have run it down to almost empty but have never been stuck with a dead watch. It also charges quickly. If I forget to charge it and I notice it when I wake up, I throw it on the charger while I shower and shave and by the time I am done and have my coffee, I am good to go for the day.
Also, with so many bands to choose from, you can switch from a rubber band for exercise to a leather band for going out at night, to something totally different for work. Amazon has tons of bands for VERY short money. Some you couldn't tell the difference from the originals and some are kind of cheap, but for the price, it is worth the shot.
When I need my Apple fix, I will treat myself to a new band from the Apple store. My watch is a very engrained to my life now and couldn't see myself moving to a different brand. I have the original version and have had it since launch