My take (really, a pretty quick one this time): Annoying characters, but I still mostly liked it -- chiefly because I think Gessen knows they're annoying, and wants us to laugh and roll our eyes at them. (Actually, Keith, from what we see of him, is fairly sympathetic; Sam and Mark, not so much.) Beautiful downtown Syracuse, NY makes a less-than-flattering cameo, as Mark's temporary Elba for most of his graduate hears (he's in a doctoral program at SU), and while it's not my favorite city, either, I initially got my feathers riled about yet another Downstater thinking there's nothing north of Westchester save depressed downtowns and toothless rednecks ... but, um, Gessen was a student at Syracuse himself at one point, so I guess he's got cred.
Anyway, digression aside, it was sometimes hard to keep Mark's and Sam's plot lines (and occasionally, love interests) separate, but again ... I'm going to assume that was deliberate. I don't know that it's a great book, or that it'll be worth reading in 10 or 20 years, but if you're familiar with the "obscure humanities scholar" type or even academic/ intellectual pretensions in general, you'll probably get a few chuckles out of AtSYLM. Best to read it once you're well past, and not still in the thick of, your angst-ridden early 20s, though.