I just finished up the single player portion of Halo, and it disappointed me even more as I went on. Mostly because it fell into an old trap: rather than come up with clever or interesting ways to make the game difficult or challenging as things went on, they just went for an old standby: overwhelm you with hordes of endlessly-respawning enemies and leave you without enough ammo to defend yourself. It just felt cheap, like they'd run out of ideas at that point.
On the plus side, the overall story was quite good (as is expected from Bungie) even though they didn't really do enough to flesh it out fully. I probably would have been impressed by this game had I played it several years ago when it first came out, but the FPS genre has grown so much since then that it just felt kinda dated.
Anyway, time to move on to another old game that I'm finally getting around to trying: Warcraft III.