I played the demo tonight, it wasn't too bad. It had companion points (as in Mass Effect pick the obvious choices to make them like/hate you) and it looked some some choice as to how to progress in the main storyline. There was one optional side quest (obvious with the whole WOW exclamation point over the head thing), so presumably you will be able to mess around.
The combat was very much button mashing, but there's a lot of different ways to focus on your skills during leveling (of course, maybe it's possible to max them all, no idea). Tons of items drop but they have a pretty easy way to compare everything to what you're wearing. New items are even marked as New until you've taken a look, so you don't have to scroll through everything to find new stuff.
Performance was good, the controls handled fine. I haven't made it through playing the mage-style character yet.
Demo was on XBox 360 (no idea if there's a Steam one yet).