Even as OP I'm hesitant to pull the trigger. I've heard a lot of negative feedback because of the DRM but to me I think that's blown out of proportion. Personally, I have two issues.
The DRM's garbage. This game doesn't need it - especially since the upcoming PS3/4 versions won't even have the DRM.
Plus, it's easy enough to blow through D3 (at least on its normal starting diffculty) all alone w/out any help. Actually, this game's MORE solo-friendly than ever before, in some ways - as there's a new Lore mechanic (these are audio-logs/text-logs you get from making it to areas, killing enemies for a 1st time, finding items, etc) and companion NPC's (bots) banter to you like crazy.
My first issue is the auction house defeating the purpose of looting and dungeons, and apparently the lack of replayability once you get to harder difficulty levels on your multiple playthroughs.
Didn't touch it b/c I played alone.
Secondly, is the lack of customization in the classes. I played through the demo all the way, until you defeat the first "boss." And I was VERY disappointed with how linear the leveling-system seemed. I didn't feel like it was MY character. I felt like I was the same as any other person playing the same class as me. Attributes were automatically distributed, and the skills were very limited. But maybe that's just how the demo version was.
Yep, the entire game is like this. It tries hard to make sure no0bs don't make a "broken build", more or less. As you level-up, you earn/unlock different "variations" of certain skills (called Runes). Since there isn't point distribution and all of that - they could've tried to tackle w/ this problem another way: they could've had each way more skills & Rune variations. But, nope - they didn't do that.