I care about Android 2.1 more than the Nexus 1 to be honest. I really don't know if it being under Google's control makes a difference. Only time will tell but let's say Google gets stingy with the updates (doubtful), you know someone is going to cook up a rom with everything anyway. It may not be official and will require rooting, but it will be available.
And like Backnblack said, those not into rooting will still get 'stolen' goodies to play with.
I would have been a bigger fan of the N1 if the speed gap was geater. But from what I've seen, it really doesn't seem to be anything to call home about. For people with a G1, Hero, or Eris on the other hand, it will be a big jump.