I've had my N1 for a month now and it's the best phone I've ever used. It's extremely snappy, no matter how much RAM I have remaining (according to Advanced Task killer). I've tried cyanogenmod 5.0.x on it and it was snappy although battery life wasn't that great. Now, I am running the 2.2 test build which is just as fast as cyanogen but with tons more battery life (i get about 36 hours with light to moderate usage)
with any phone, however, it isn't always perfect.
I downloaded Multitouch Visible Test to experiment with the touch capability. When crossing axes, the touch points get inverted which isn't good. if you have a finger on a screen already, and attempt to touch a different point, the second point will end up being leveled with the first point. that's why you aren't able to hold shift on the keyboard and attempt to type a capitalized "O". this cannot be fixed with keyboard replacements out there in the market.
this is also the reason why you cannot type as fast on the on-screen keyboard. when you type, you have to make sure your first finger is lifted OFF the screen before you touch the screen with your second finger. otherwise, the 2nd finger may not be recognized
here's a video show-casing this. it's my only gripe with the phone.http://www.youtube.com/watch?v=qzhUzq6bTPg
as noted in the youtube comment:
Nexus One has a crap Synaptics ClearPad 2000.
That is why the multi-touch on the Nexus One simply doesn't exist and it won't ever because the touchscreen manufactured by U.S. based company Synaptics is a piece of crap.
Google and HTC should put their eyes in details less than in marketing has: Big processor and open fameworks.
It's a shame.
edit: just started using swype. it's amazing and incredibly accurate (almost mind-reading accurate). since swype requires dragging your finger across the screen, there's no worries of any multi-touch issues. there goes my only complaint!