I think the HD3000 is better than the nvidia 9400, but lags behind the newer nvidia integrated gpu, the 320m, unless the game is written to take advantage of the intel (ie, newer games).
After hearing all the wailing and lamentations on this forum about the HD3000, I initially hesitated. But coming from a 2008 aluminum macbook with the 9400, I don't have a single regret about the 2011 air.