I really love mine, much more than I thought I would.. I only purchased it to scratch an itch.
I done a lot of research and seen a lot of complaints.. non of them bother me, I guess I just didn't expect it to be something it's not, I knew it would just be an extension to my phone.
The size is perfect for my wrist.
The weight is perfect, I have a Kinetic Direct Drive, rather heavy, I would generally only wear it mon-fri 9-5 (the working day) as it gets heavy and is not comfortable to wear when lounging around or tending to the children... The AW is on pretty much all day every day.
I feel like the speed is fine, i haven't noticed it being slow at anything really.
Text message dictation, wow.
Notifications on the wrist are really handy, I hate phones being glued to everyones hand, myself included.. this lightens the load a little.
Battery life, for my usage, is fine. I charged it today at 11am, it's now 9pm and still on 70%... i've been playing with it throughout the day and receiving notifications all day... I don't have any complaints with that, it will shortly be going back on charge ready for tomorrow.
It actually looks much better than I thought, at the announcement i felt like it looked huge, horrible shape, childs toy.... in the flesh it's a really nice size and the stainless steel version is just as nice as a regular watch.
I could go on, but my advice to anyone thinking of buying one, don't expect more than you know it offers. It's a great extension to the iPhone.