The Carnegie Mellon experience can be summed up in a single sentence: It is what you make of it. No matter which program you study, the course load and subsequent work are rigorous. The weather is iffy, and the social scene is nothing compared to Penn State or other schools of similar caliber. Having said that, it is easy to form close relationships with teachers that will last long after graduation. You are also guaranteed an education that spans all of the disciplines, not simply your major(s) and minor(s). CMU has arguably one of the best orientation programs, and the friends you make during that week are likely to be with you for the long haul. Sure, it might rain a lot, but the campus isn't that big, and a CMU ID card allows you free access to all of the buses in Pittsburgh. As for the social scene? While there aren't a ton of all-out "ragers" every week of school, there is a fair amount, especially at the beginning and end of each semester.
For some, the positives just don't outweigh the academic and social challenges. Not everyone here will tell you that they love it unconditionally. However, if you are even considering CMU, it's not because you are looking for ragers every weekend and beach weather. No—students come to CMU for the academics, and on that, the opinion is unanimous. This school is a great decision for someone who is serious about learning as much as he or she can—and not simply academics, but culturally, as well. There is a reason students come here, and the not-so-bad social life is simply a pleasant surprise.