When I applied to MIT, I didn't consider whether the people of Boston would be as friendly as the people of Wisconsin. I probably wouldn't have given it a second (or first) thought, except for a conversation I had with my school librarian. She asked me what I would be doing the next year, and I told her about MIT. Unlike most people I had told, her reaction wasn't just to congratulate me. She said "... but... aren't people on the East Coast a bit... unfriendly?"
Now, to be fair, I still can't answer that question entirely. Most MIT students don't leave campus much. There are so many awesome people to meet and activities to try (and so much work to do) at MIT that I haven't spent a whole lot of time in Boston. That's actually point number 1: This isn't a very important question to answer, because MIT is the community you will spend most of your time in, and it is plenty friendly.
As for Boston though, it might help to share a few anecdotes to give you a picture of what the city is like. And, in the comments please let us know if you have other anecdotes to add.
Anecdote 1: My family came to visit me about a year ago. My mom was always striking up conversations with people on the subway! She would talk to them about their children or where they were going or how to get where she was going, all the time. Most people in Boston would not initiate a conversation with a stranger, but they will talk to you if you initiate the conversation.
Anecdote 2: I left my purse on a city bus a few months ago. When I called my phone (which was in the purse) the woman who had found the purse answered, we met, and I got my things back. A similar incident happened a couple of months later; my wallet fell out of my pocket as I was crossing a street, and the man who found it looked me up so that he could return it. Maybe I'm just lucky, or maybe this says something about the residents of Boston.
Anecdote 3: One of my friends who lives in an apartment in a bit of a shady area (not near MIT) was mugged a few months ago, and was badly beaten up.
Anecdote 4: About a month ago, on a cold rainy night, a city employee made me get off of the subway because I had a bicycle. Never mind that I had already paid, never mind that it was miserable out, never mind that people with strollers and large packages are allowed on - rules are rules. The guy was also a complete jerk to me. I had to sit around for an hour until 7pm, when I was allowed back on (the reason the rule exists is so that during 'rush hour' the subway doesn't get overcrowded). On the brighter side, once the jerk went off duty his coworker let me back in for free since I had already paid once.
Anecdote 5: Yesterday, my boyfriend and I rented a Zipcar. We were way out in Weymouth when the car broke down. The woman whose driveway we ended up in invited us in for tea while we waited for a tow truck to come!
Anecdote 6: One day last year I stumbled upon a giant outdoor dance party, put on by the city to increase community spirit. It was nighttime, and colorful lights lit a crowd of hundred of people, dancing in the street outside of City Hall.
These certainly don't sum up the whole city, but they can give you an idea of what to expect. Boston is a city, and it can be a little dangerous. On average people are a bit more direct here, which I think is what my librarian had actually picked up on. When they mean "no," they are more likely to just say "no" than "sorry, I would, but... ." In my experience though, most of the people I've interacted with are decent people who are perfectly willing to help a stranger out. Some will even dance with strangers in the street. Really, I think that you get a similar mix of people here as anywhere else: some friendly, some not, some nice to you if you're nice to them first.
What have other people's experiences been, coming to Boston for the first time? How are people different here? What other questions are admitted students thinking about? (And by the way, congrats if you got in! Come hang out with us for CPW!)