I played Halo 3 at a friends house. It is, as Strongbad said, much more like Halo 1 than 2. I was a huge fan of Halo 1, but horribly disappointed by 2, and 3, while hardly feeling "next gen", is still pretty fun.
Also, Legendary on Halo 3 isn't exactly challenging. More like annoying. Pop out from behind that rock for more than a quick shot at one of the many snipers all around you and instant headshot. Still, I actually enjoyed the campaign again, like Halo 1, instead of being bored as hell (I.E Halo 2).
Squiggly Line Squiggly Line Squiggly Line