Played the demo - My initial reaction is that it seems like it could be quite a bit of fun, however, it's not remotely original and I wouldn't expect anything ground breaking. It plays exactly like an MMO, but it's single player (collect herbs/profession reagents, MMO style talent speccing, stuff like that) ,the art style is very similar to Warcraft and it's generally very cliche characters/story, etc.
That said, the combat is smooth and flows great, tons of special moves and specs to play around with. Lots of button bashing in the early stages but that'll change later on, the combat is sort of feels like God of War.
Played this last night and i gotta say i really like it! Couldnt put it down once i had started playing, think im gonna buy it. The Mass Effect 3 unlockables are a nice bonus as well.