Not super great, I would guess? For state residence advantages, you're looking at what kind of options are exclusive to you as a resident of that state. That's why living in Texas or Ohio is so great.. so many schools and a large in-state preference at most of them.
Massachusetts has, I believe, 4 medical schools. And 3 of them are private, so you are likely looking at a lot of competition among in-state applicants at a school that strives to take students from all around the nation. Also, one of them is Harvard. And another one is BU. Both are very competitive. Tufts and UMass are good schools to apply to if you are not the very cream of the crop, but again Tufts is private and likely doesn't have a preference for in-state students.
Of course, if you went to one of these schools for undergrad, that might help?
I have thought about it before and have had friends apply from Massachusetts. While I don't have first-hand experience, it seems less than ideal.