An article at GamaSutra about 2004's Most Creative Games quotes Coray Seifert of Large Animal Games as crediting Halo 2 for being more than just another pretty FPS:

I know I'll take some flak for this, but I really enjoyed the creative implementation of Halo 2's new gameplay features. To fans of the game, it felt intuitive and familiar, but it also gave the player a lot of new toys to play with (dual wielding, new vehicle options, etc.). It was also accessible for folks playing the game for the first time, which you have to respect as well. No, its not the next Sims or Katamari Damacy, but I think its very creative and original for a big-budget sequel.

Thanks Joystiq.