I've had a space grey sports Apple Watch since launch. I thought initially that it's a lot of money to put down for it but as an iOS dev I figured I should at least learn how they work.
It's a lot more durable than I thought it would be. I wear it everyday and so far no scratches. The band still looks like new even though I thought it would get dirty pretty fast.
I installed a LOT of apps on it when I originally got it but soon got rid of them. I basically only use a handful of third party apps on it now (PCALC, OmniFocus, Evernote, 1Password, LIFX). The majority of use is with the built in apps.
I use the activity app every day. The reminders to stand up are good considering without them I could easily get lost in work and spend the whole day sitting down. Being reminded to stand up actually makes me drink more water too because I use the time to go get some. It's kind of weird but I really like this aspect of the watch. The achievements for reaching certain activity milestones appeals to my gaming side as well.
Siri works great. I use it a lot to set reminders, timers, reply to messages, enter tasks, etc.
I basically stick with the same watch face now. I tweak the colour of it every few days.
I find Digital Touch completely useless. Not many other people I know have an Apple Watch and the few who do rarely use it. It feels really gimmicky.
I like the maps integration. Set a location on my phone to go to and the watch will notify me when to turn left or right. I find it works surprisingly well.
Reading messages on it is one of the thing I really love. Being able to quickly look and see if I message is important on not is great. Not having to pull my phone out all the time is awesome.
Reading mail is ok. I wouldn't use it create long replies but I find it good for quickly looking to see if there is anything important.
Answering / Placing calls on it just doesn't work for me. I feel weird doing it. It's good though to see who is calling. I have used it a few times to answer important calls while driving. It worked really well with me just driving as normal and not having to actually bring the watch up to my face.
Apple Pay.... if only we had it in Australia. I think I'd use it a LOT.
Overall I think it's worth it for me. I'm not spending as much time grabbing my phone and looking at stuff. I briefly look at the notification on the watch and then work out if I need to address it or not. It's made me be a lot more active, drink more water and generally be healthier. I think if I was to get rid of it now I would definitely miss it.