Began playing this on the PC today. So far, it's really good - a bit over an hour into this thing.
It feels already like a major improvement on the side-quests - even though there are general quest types (Race, Beat Up, etc) - the NPC character models and voice-work are much more unique in comparison to the original.
Graphics looks great. And my PC is running this AC2 MUCH better than the original AC ran on my PC - higher res (1024x768) and higher graphic settings (mostly 3's). They obviously tweaked the hell out of this engine. Very impressed w/ that.
Nothing to say about Ubi-DRM yet. Ain't ran into any issues...YET.
EDIT - 8-21-2010:
I been doing some of those "tomb" missions (side quests), where you go after The Assassin's Seals - which feels like something right out of a POP games - where you basically do all kinds of crazy platforming, jumping, flipping, vaulting, acrobatics, and gymnastics to get from starting point to some ending point. Freakin' awesome.