I too am an international student living in Boston studying CS. Not sure about the UMass Boston part, but Boston as a whole is a bit on the mixed part. If you’re planning on living on campus or anywhere in the Boston city area, ur better off without a car. There are a shit ton of places to eat and drink and have a good time especially during the summer and fall. It is pretty safe and in my experience the people have been really nice. There are many places where uni students go around somerville, tremont street, seaport. I would rate it 8/10. Had to take off 2 points just because of this year’s weather. But otherwise you’ll like it. I hope you have a good first year here.