My friend bought Halo CE: Anniversary for me so that we could play it together, and I can hardly fault him on his choice as Halo does not emulate very well on the 360, and we both like it a lot.
I love that you can play the single player campaign co-operatively online, however, I'm deeply disappointed that the original Halo: Combat Evolved deathmatch, etc. suite has been more or less snipped.
While I don't go out of my way to buy games strictly for the competitive multiplayer suite (nor does my friend; we have very similar tastes in that regard), I had a lot of fun with Halo, and it would have been awesome to have that upgraded and given the XBox Live treatment like the co-op campaign. Instead, you get some remade maps for the Halo Reach online experience. Luckily, Halo Reach is close enough to the original Halo, even with jetpacks, special shielding, sprinting and the like.
It just would have been nice...
That said, it's still a great package for the price; Halo is a great game, and it's made all the more better being able to play it co-operatively online or off. And the HD job is stellar.