Butler Library is basically a black hole that sucks out your soul. Once you go inside, you have no way of knowing what time of day it is, whether it's sunny or rainy, or whether the world has exploded or not. Hours flash by at a suspiciously speedy rate (I personally suspect a time warp).
On top of that, a library full of silent people doing their homework next to each other can be an unexpectedly awkward social scene. When you enter a room, innocently looking around for an empty desk, people stare at you contemptuously, as if to say "Why are you interrupting my studying? Go away, intruder!" And once you manage to find a seat, every cough, every shuffle of your feet, is magnified as it echoed around the silent hall. As a friend of mine put it, "It's like all the awkwardness of social interaction, but without the talking."
However, I would argue that Butler is the best place to study on campus. First of all, the awkward social scene puts a kind of pressure on you to actually do your work. If you go on Facebook, the ten people sitting near you who have a perfect view of your computer screen can see that you're going on Facebook. Their imagined disapproval keeps you on track.
On top of that, the entire terrifying atmosphere of Butler just makes you want to get out of there. Tell yourself you're not allowed to leave until you finish your work, and you'll be done in no time.
Finally, the silence of butler is a great conduit to utter concentration. There is literally nothing to be distracted by.
So try out Butler, even if it's only in a case of emergency when you have a gigantic, nasty essay that you need to just sit down and pound out. It won't be fun, but you'll get the job done.