Well, clocked up 7 hours on my Wizard now, just in to Act II and I have to say, this game is amazing.
The graphics are just awesome despite it not being that harsh on your PC, the physics engine is just hilarious when you KO a mob and it just flies across the room. The spell affects are also really really good, and I'm loving the system where you can customize your spells to how you want them to be with various runes etc. The ability to go back to town at any time (when you're not fighting) by pressing T is also amazing, because once you're back in town you simply click on the portal and then you're straight back where you teleported from, so no need to drop items to make room for more valuable ones, simply sell them!
The story and cut scenes so far is really solid, the cinematic are really, really high quality as you can see from the trailer.
My only gripes with this game at the moment is that the servers are, as expected pretty laggy sometimes, and it can take a while to log in. But I'm sure that it'll get sorted shortly. There are ofc a few bugs as you would expect from any new game but none are game breaking.. Apart from one with the Demon Hunter where if you give your companion a shield that you've already equipped you cant log in.. XD