Nexus one reception blows. I've been on at&t in NYC for years. The reception used to suck but over the past year has really gotten very strong. My iPhone 3GS & my Blackberry Bold work perfectly on the network. Unfortunately My n1 has a MAJOR issue where about 2 out of every 5 incoming calls (approximately), I will answer and the person on the other end cannot hear me. I can hear them fine but I have to hang up and call them back and then everything is fine. It's the most frustrating thing in the world. The phone also definitely drops more calls than the others devices but not really at an alarming rate.
Edit: also wanted to add that it's definitely not due to my finger being held over the 2nd mic. I'm very careful to avoid that.