Personally, since I've been born and bread on a keyboard and mouse playing Doom, it seems like the more comfortable tool for first person shooters, but it's always driven me crazy that I don't have a joystick whenever I come accross a great third person shooter or flight sim style game. And I think since Halo 2 has elements from all three, it's a gret oppertunity to bring the tools that make you feel the most comfortable, with the areas they feel best. It'd be nice to be able to run in guns blazing, mouse in hand, then jump in a Banshee or Ghost and whip out your joystick, or the other way round, it's just nicer to be able to accomodate any style of gameplay within a game with the device of your choice.