The Bleachers at Yankee Stadium have a reputation for being loud, ridden with foul language and a terrible place for visiting fans to sit. So if you're bringing the kids or coming from out-of-town, spend a few extra dollars and site elsewhere.
As you look closer, you can see why the fans might always be in a bad mood -- metal bleachers and a high likelihood of having an obstructed seat would cause anyone to be a little irritated. Never-the-less, if you're a Yankees fan on a budget and just want to catch a game, the Bleachers are your best bet.
Completely avoid Sections 201, 239 and rows higher than 10 in Sections 202 and 238 -- that is unless you like having your view obstructed by the center field structure.