I was at work the other day talking with a coworker who also had a Nexus. My office is in a strong 4G area. We were talking about our phones when another coworker came over.
This other coworker had a Rezound. He runs a speedtest and got 20Mbps. The coworker with a Nexus and myself got awful speedtest results because, neither of us had a 4G signal. I rebooted my phone and upon the reboot, I had a 4G signal. But, when I ran speedtest, I only got 2.3Mbps.