Amherst: The Big Picture
I think Amherst is the perfect size. While you'll be able to recognize most faces on campus pretty quickly, there are always new people to get to know. People know who's who and can be up in each other's business most of the time, but that's only a problem if you do something stupid that gets you more attention than you want.
The administration is excellent; they have very specific goals and seem to do a lot to accomplish them. There's very little red tape and even the important people are pretty accessible. You'll occasionally see deans and even the president of the college in the dining hall or the gym.
Amherst Academic Life
Amherst's academics are excellent. There are no graduate students, and the focus on teaching is emphasized. My professors all know my name, and are more than willing to spend time discussing ideas or how to improve a paper. There are no academic requirements, other than taking a first-year seminar and choosing a major, so for the most part there aren't students in your classes who are just there to check something off a list. To do everything correctly, you have to spend a huge amount of time doing schoolwork. Some people spend almost all their time working, most people do most of the work and do fine, and some people do very little work and get by. Amherst is definitely geared toward learning for its own sake (at least in the humanities--I'm not sure about science or economics) but there are also great campus resources to help you get a job later.
Amherst's Student Body
I don't think there is a particular kind of student who would feel out of place at Amherst--although it's small, there are all different kinds of people and groups. There are definitely some very intellectual, somewhat pretentious people here, and there are also some somewhat frivolous superficial types, but for the most part, people are friendly, engaging, and interesting. Some students are very politically aware and active, and get frustrated with those who aren't, but overall the student body is well-informed.
Amherst Student Activities + Social Life
Many people here play sports, and a lot of the parties on campus are thrown by sports teams. The college throws "alcohol-free" parties every month or two; they're usually sweaty dance parties where people who've already gotten drunk congregate, but they can be a lot of fun. Most people have small groups of very close friends which are part of bigger social groups. Other than sports, a cappella singing is probably the activity that the most people are involved with.
Amherst Naked Truth
I love Amherst, but it can definitely be very stressful at times. Most people here are huge overachievers; they're balancing schoolwork with a sport and another time-consuming extracurricular without neglecting their social lives. Most people are incredibly driven to succeed, although not necessarily in terms of getting a great job and being rich. Sometimes it can get to be a little much.