Although I'm what, three years too late? to complain about Halo, I'm going to do it anyway.
When the game first came out, the standard criticism of its mid-game levels was that they were too cookie-cutter in their repetition, like Bungie just copy-pasted big chunks of architecture through the game. I can see where these complaints come from, but it didn't bother me, because at least you felt like you were making progress.
Halo's biggest sin is not that the level design is a little repetitive. It's the parts in the game where the designers literally lock you into a room and then flood it with repeated waves of enemies. Having restarted the game on Legendary, I fought through a few of these, making it to the first level on the Covenant ship, before finally giving up in disgust. Belle can attest that there was a lot of cursing and shouting along the way. By the point where I gave up, there had been three such situations: one is the initial crash-landing zone, where dropships keep swooping in, followed by the elevator lift that keeps dropping enemy squads, and then finally the first room of the Truth and Reconciliation. That one was the final straw.
Halo fans tend to repeat the same two points over and over again when praising the games. First, they talk about "30 seconds of fun" to defend the fact that Halo never changes and combat never gets more complex. Second, they refer to a pyramid of weapons--firearm, grenade, and melee attack--as being the main balance of Halo. You're supposed to swap between these three options pretty much equally, I guess, and if you can't, you won't get very far. There's no allowing for another play style--I think melee combat in shooters is ridiculous, for example, so the whole "magic triangle" is pretty much ruined for me from the start.
So it's not the endless corridors that get to me. It's the fact that when Halo decides to lock you in, the only option is to fight the way that Bungie wants you to fight: close-up, with no subtlety or potential for evasion, and without any indication when they'll let you go. You're discouraged from trying new approaches, or bringing your own style to the game. In the end, I just don't like the way Bungie wants me to play.