Wile mechanically great, the game is crippled by an unfathomable amount of repetitive level design.
But i just can't enjoy the campaign most, if not all Halo fans, tell me it's the best in the franchise. And i'll tell you the reason a little later, first let me get the good stuff out of the way.
The sound/music. The music in this game is simply awesome. From the moment the menu pops up, right 'till the end, the tracks were fantastic, atmospheric and managed to create a great ambiance wile i played. The sound design is extraordinary in its quality considering it's a 12 year old game; Every enemy, every gun, every step and every explosion just feels right.
The mechanics. Besides the fact that they're a bit floaty, there's nothing that hindered me here at all; Movement is fluid and responsive, the gunplay is still as enjoyable as it was back then (partly because the enemy AI is competent and provides a great challenge), and the weapons themselves all feel right right and are a joy to use. There's even a decent variety of weapons at your disposal because you can pick up what your enemy has (after you put them out of their misery, ofcourse).
And now the bad stuff. Actually, i wont bother nitpicking my minor complaints that i could have easily ignored if not for my huge problem i have with this game.
It's simply a painful slog trough endlessly repetitive environments and endlessly repetitive enemies. This basically killed my enjoyment, and bored the living day lights out of me. And i'm not just talking about the Library or the Flood levels; And if i had to pull an estimate out of my behind, i'd say that at least 70% of the game has a ridiculous amount of re-used assets and copy-pasted level design throughout the campaign. I mean, it got so ridiculous at one point that i was literally walking forward through the exact same corridor & room design for like an hour, over and over again.
Fighting the same enemies, over and over again, and this is what i really couldn't stand. If they (Bungie) would have, at least, designed slightly different enemies just a little bit more throughout these painfully repetitive environments, i would have enjoyed it so much more. Making up different tactics, experiencing some new moves, etc.
.. Overall, yeah. Loved Halo 2. Liked Halo 3. Cannot, and will never comprehend why people love CE's campaign. It probably is the most influential console first person shooter ever made, sure.
But the game is crippled by an unfathomable amount of repetitive level design, that no reputation, hype, fanboy or nostalgia goggles could ever hide.