I feel like Halo in general has been a bit behind technologically, with its gravity-defying spartans, limited player animations, weak sound effects, and archaic-feeling gameplay. But Halo 2 Anniversary actually managed to attain a surprisingly modern feel. The increased resolution and frame rate, combined with the new (and excellent) sounds, textures, and lighting, make this game feel like it actually has a firm place in the next generation, even though it's really just a fancy shell on a decade-old product.
The new weapons and vehicles felt great. I can't wait to jump into some custom games and start tearing people up with the warthog.