America is much better than most people give it credit. The +5 bonus on continent is exceptional. It removes the AI advantage for deity so you can be slightly ahead of them on combat strength (I believe the deity bonus is +4?). This allows you to both be much better at beating back rushes and also lets you do some great early conquest. Plus, now that they have a wildcard slot instead of diplomatic, they are even better. I actually really enjoy playing as America, though they obviously aren't as strong as Nubia or Aztec.