1. Much better than the Thunderbolt or Incredible in 3G signal. By about 10dB.
2. Slightly worse than the borrowed Razr by 5 dB.
I can't talk about 4G as I'm not in it's area enough to gauge a difference. When I was in San Antonio, I got 22 down and 11 up. And I had a 4G signal in an office where I didn't have one with the Razr.
I must admit, though, that at least the Nexus can hold/reconnect (quickly) a data signal. When the Razr dropped off a data network, it could take 30~45 minutes for it to "see" a new data network. It was very annoying especially while driving. Handoffs on the Nexus seem fast.