Interesting read from an iPhone developer who bought a Nexus One.

http://iphonedevelopment.blogspot.com/2010/02/nexus-one-from-iphone-developer.html

Basic summary, the Nexus One is the best smartphone out there when excluding the iPhone. But when compared to the design, user experience decisions, and a few other factors on the iPhone, the Nexus One misses that last 10%. Mostly due to decisions like placing a touch sensitive home button right below the spacebar when in portrait mode leading to the occasional accidental application closure. He's also puzzled about certain performance issues at times, considering the hardware.

Definitely a little biased, but it's probably a good viewpoint for any iPhone owner looking at the competition for a potential phone replacement.