For me Halo 1 was the best Halo they ever made. At the time I played it on PC so I understand my experience of multi-player is somewhat better than the Xbox players at that time (which was rubbish supposedly - Halo 2 kicked it off for Xbox Multi-player).
For me Halo Anniversary feels weird, but in a mostly good way. The updated graphics are really good, but the engine hasn't been updated so Master Chief still runs up ladders rather than climbing etc. Also, the updated graphics make it feel like you are playing a new Halo, and yet there are none of the functions of Reach (I particularly am missing Sprint

). It's little things like this that betray the true age of the game, despite the fantastic graphics.
But that having been said, even in 'Old Skool' mode it's still one of the finest Co-op campaigns there is so I'm not bothered at all.
