Sigh, I may be attacked for this but halo is possibly the single most overated game in history, seriously, I would take the original unreal tournament over it any day, and I'm not even that big of a fan of unreal tournament.
Its basically a bunch of arcadey, actiony, special effects-ey. eye candy, like watching the matrix sequels, nice special effects, some decent other things, but almost nothing new, and most of the stuff thats close has been done FAR better in other things.
My thought about halos success is that its THE game to have for the XBOX, its hyped by the giant microsoft, and it is not a BAD shooter for the console, and the console has almost never done a decent shooter. Maybe its "stunning" for all those beer n' pretzels, tv, after school gaming teen, but to anyone who has been around PC games for quite a while, its just not that much new. Computer games have had great (and better) graphics, computer games have had great (and better) gameplay, computer games have had great(and better) sound FX and musical score.
In my opinion, decent as a general overall game, good for a console game (which tend to be total arcadey action crap ALL the time) and great if you have never been in with the greats of real serious gaming on the PC.
I don't know, maybe I'm being a little to hard on it, but it kinda symbolizes all the things that have made me angry with consoles, how people say gaming is "moving" over to consoles, when they still don't have a single really could strategy game (the creme of the crop of gaming IMHO) and the large scale developers attempts to appeal to the all important "arcade" gamer, it just kinda annoys me.