Pros
* Top-notch research institute with world-class faculty and very smart graduate students and post-docs, many of whom are also very friendly and normal. * Pleasant weather and a pretty campus in a terrific city (Pasadena) * Some of the outlets for work-life balance are surprisingly good: the gym and music groups are excellent, especially considering Caltech's small size; great student-led clubs for alpine activities, kayaking, surfing, etc.
Cons
* It can be difficult for both single men and women to meet eligible dating partners. This is probably true of all small technical schools, but it's nevertheless an issue. * Some advisors turn out to be much less charismatic once you actually work for them. Talk to current students of any group before you join. * Teaching quality varies widely. Some courses are excellent, but more are poor and most hover around meh.