Brian Ha, Yale '05
I think James's first sentence is key: It is what you make of it. It's a diverse campus and different majors have vastly different academic challenges. If you want to take it easy once you get to school, you certainly can, and there are programs that will accommodate that desire (with the big caveat that even the most lax student at Yale will likely be more driven and competitive than your average student anywhere else).
But I think that those kinds of students are a minority. Think about the types of students who apply to Yale; they are, by nature (or nurture), driven and competitive people. That's not going to change once you're in school. BUT what is different is the environment you're in. In high school, you are one of a few who compete at this level. That makes you stick out and seem overly competitive. Once you're at Yale, you're surrounded by people who all have the same drive. We embrace that drive together and frankly, that what keeps Yale an elite school. No one is ashamed of drive and ambition at Yale, it's celebrated.
So are students still really competitive at Yale? Absolutely. Does it feel like a problem? Not one bit.