I did not play the x-box version so it is all new to me.
Halo is a great looking game. The only thing lacking is AA. I see some jaggies at 1280X1024. I have a new system with an fx5900u and with everything turned on there was only a few slow downs when surrounded by a lot of enemies.
The gameplay has a nice flow. Just when you start to get tired of shooting aliens the same way the game throws you into another area or a veichle.
I don't like the console way of saving the game to checkpoints but that is my only major complaint.