Most of my complaints have already been said, including:
-annoying second person
-too much telling
-relying on overused stereotypes
-The style of the story seemed to indicate it thought itself pretty important, which clashed with my apathy.
-It states that they can't cross between floors, and then they do.
In addition to that, I had extreme trouble believing that a world as this could ever exist anywhere.
-Where does their food come from?
-Where does their sewage go?
-Why don't the grenades burn the house down? Where do they get grenades anyway?
They've been living here for at least 3 generations, probably much longer. Living there that long without the slightest mention of the answer to these questions demotes it from story to allegory. Not that there's anything wrong with allegory, and while allegories are interesting in philosophical discussion kind of way, the setting is so clearly artificial that the people must also be artificial. Because of that, I don't care in the slightest what happens to them.
On top of that, some of the actions they took uniformly as a society struck me as terribly unrealistic. The basement folk all cut off their legs because they were afraid the angels would reject them? I can perhaps believe one or a few people doing that, though they'd have to be very mentally unstable folks. But a whole society systematically doing this for generations? I can't believe that. Not even a single person says "Hmmm, maybe before maiming myself, I could walk upstairs and say hi." On top of that, how does maiming make it any better? "I'm afraid the angels will reject me, so I'm going to MAKE SURE they reject me because I'll never make it up there. That'll teach them!"
I've said before (and I"ll say again) that I like a story that carries a message, but this is a message that carries a story.
I did listen all the way to the end, simply because some of the philosophical ideas were cool.