Okay So I managed to snag a 42mm Space Grey Aluminium Sport Watch for pickup at Doncaster. Was particularly nice walking in and just having it handed to me while other people asked if there were any available and were told "no". If you want one, keeping an eye on the iOS Apple Store app is the best way to do it.
Still getting used to it. I didn't have the first watch so everything is shiny and new for me, probably lucky to start on WatchOS3.
What I love: Siri. Seriously, I use it to add stuff to our shopping list, for timers, and other random stuff. It's just really handy being able to do stuff like that while your phone is in your pocket, or even in another room.
Notifications. After having a Pebble and the Garmin Vivoactive, notifications on the Apple Watch are just awesome, and actually LOOK beautiful. I just love the screen. It's worth having to charge it every day for the beautiful screen.
It works very well in sunlight, you can read stuff easily.
Playing with watchfaces etc is fun but I wish they would open them up to Developers to create completely custom ones, not just the complications you can add to the existing ones. Apps should also be able to include custom watchfaces. It's a no brainer, can't believe Apple haven't done it simply for the fact that they would make money out of it.
Activity tracking: All the functionality is good, but I wish they would let you export/share activites with other services like Strava and Runkeeper. Major failing that they don't. Waiting for Runkeeper and Strava to release their own Series 2 apps that take advantage of the in built GPS.
Podcasts. Why on EARTH Apple don't let you sync podcasts, is a major failing. I don't need many, just a few. But I listen to podcasts at the gym and being able to pair my bluetooth headphones to the watch and listen to podcasts would be awesome. I can't believe they, or a third party like Shiftjelly haven't done this.
I've found a great app called Gymaholic for recording workouts on the watch, exactly what I wanted.
All in all I'm pretty happy with the Watch. I originally ordered the Nike+ model but when I thought about it, it wasn't worth the wait til they are released at the end of October.