After a few days, I still love my Nexus One. It's very fast, nice, slim, ... With this phone, Android is now on par with the iPhone, at least with the 2G and 3G ones - I don't know for the 3GS as I haven't use one so far.
But from times to times, the Nexus One starts to have a very strange behavior, when for example, trying to click (touch) one of the buttons bellow the screen triggers a completely different action than what you ask for. It seems to happen more frequently when a lot of apps have been opened and the phone hasn't been restarted for some times ... It also seems that using the Advanced Task Killer to kill some tasks only makes things worse. The best solution I have found so far is to power down the phone and power it on just after. As everything goes right just after the reboot, I suspect some app to behave the wrong way.