This is a great spot! I was in Boston for a three day event at TD Garden and I really liked this for a few different reasons.
1) It's location right near a MTBA station made it super convenient to get into downtown. Plus, being such a short walk was nice the night I got back around midnight. 2) Everything was described perfectly in the listing, in the directions on how to get in, and things were labeled really well there. Literally no confusion, which I really appreciated. 3) It really felt like I had my own space while I was there. Sometimes places with more that one rental room make you feel on top of each other, but I never felt that way during my stay and there were people in the other rooms the whole time.
While it didn't bother me, the "Cozy" room is very small. I wouldn't recommend it for anyone even remotely claustrophobic. It did have a window and an air conditioner, which helped, but it's tight. I didn't mind at all because I only had a carry-on size suitcase and was really only there while sleeping, but I could see why some would be uncomfortable in that room. Their other rooms would be more suited if you need a little more space.
Overall, great experience and I would definitely stay there again!