I disagree. Halo is a game I didn't play in full (no XBOX of my own at the time) but even I heard how bad the Library was; or more specifically how much the flood sucked to fight (they apparently do not get "fun" until Halo 3)
The issue with having the flood as this unstoppable horde that "you can't stand and fight because they just keep coming"... is that the level keeps having you stop to do *exactly that* and you need to succesfully do so in order to progress. If you want the Flood to be an unstoppable horde that you can't fight, then the Library should've been a running section. Hurry to get to the next door (which would have doors on both ends, a la an airlock; there is at least one area like that as I recall) before the horde overwhelms you. Take a moment to rest and recover, maybe find some ammo... then the next area, and so on. At least once, some of the flood would break into the room and you'd have to fight them.
That last one would actually be great.how I'd make it worse:
make it so you have to solve meaningless puzzles that have nothing to do with anything at random doors. it isn't even consistent.
put in a labyrinth segment
make the tide of small facehuggers never stop coming. just an endless stream of them. forever.
add in ice physics.
add in books. but they're all about ancient Forerunner smut.
make all the flood thomas the tank engine
replace Guilty Spark with GladOS.
"Failure to eliminate all Flood signatures will result in a poor mark on your performance evaluation.
Followed by death."
"It's not just any parasite. It is the deadliest, most unkillable and unstoppable parasite that ever existed. And you just let it loose across the only thing that could stop it.
*clap*
*clap*
*clap*
Good, my slow clap processor's still working. Now let's get to the Library so you can get to fixing this mess. Or die horribly. Either way I'm entertained."