Yeah, I'm still very much interested in Geist (and if you order it now you get 100,000 free HBC points (or something like that)!! Not sure how much that's worth in real money - probably $1, but YEAH!)
Anyway, there are a few things that concern me. First off, the lag that is likely to occur during the action-heavy segments (including multiplayer). The videos didn't really tell much, but there is a chance that it will stray from a steady framerate.
Also, the character models and the movement look quite awkward. I really don't care about this, but you can tell that the polish isn't really there.
And finally, I fear that the novelty of always possessing objects/people/animals to progress might wear off quickly. Sure, there are a whole host of situations and ideas that can be created from this mechanic, but it's sure to become a bit repetitive at times. The action can redeem this though, so it's not that bad.
I don't know how much work was put into the multiplayer, but I'm not hoping for too much. A decent multiplayer mode would be good enough for me.