another Tufts student here, matched in IM..
IMO:
Pros: located in a beautiful city with a huge focus on education, great variety of hospitals, including a major affiliate in Western Mass (Baystate, a very nice happy place) and several places where you get to work with faculty, residents, and students from Harvard, BU, and UMass (i.e. Lahey, Faulkner, NWH, Metrowest). Very strong nationwide reputation and great residency placements all around.
Cons: as ears mentioned, NEMC has its share of problems, and the teaching/attitudes in certain departments there really leave a LOT to be desired. The Ob/Gyn course director and residents there are really pieces of work, to put it nicely. I was willing to risk going unmatched rather than rank NEMC for residency, though fortunately, that turned out not to be an issue. The administration is also notoriously unhelpful and unfriendly to many students on issues like schedule changes and ANY kind of academic difficulty, and don't go to anyone in the OSA who doesn't have an MD for advice on residency applications unless you want your schedule totally ****ed up. Lots of people really get obsessed with grades and competition and prestige too, which can be hard to take, but not everyone is like that.
The cost bites too, I totally agree with Tom Slavin that you should go to your state school if you get in. It's hard to say whether people as a whole are happy here as many of my original classmates are taking the 5-yr route to do research, have babies, etc and I don't keep track of them that well.. Personally, I will miss living in Boston next year as I love the city, but am very happy to be moving on to a new med school system for residency. Good luck!