Great location for sightseeing
We had a king room atrium view on the 8th floor - more than generous space, clean and sparse in design/furnishing. The room also included one upholstered chair and a round kitchen-like table with two chairs. A large built-in desk/entertainment unit included tv and a wonderful stereo system with built-in speakers in not only the room but also the bathroom.
Being an old building you can crank the tunes without upsetting your neighbors!
The only natural light coming into the room is via the hall atrium which may make some folks feel somewhat claustrophobic (no windows). Since we didn't spend much time in the room this was not an issue. 
The only real problem we had were the lack of lamps - the ceilings on this floor may be 12' high and have recessed lights (which are not bright at all), the only other lights are two very small wall-mounted on either side of the bed. Even with the ceiling and small bedside lights forget reading in the evening - bring a flashlight.
The room was clean and the bathroom had a very large shower; the sink was built into the largest counter I have ever seen in a hotel - so much space - it was wonderful.
The hotel includes coffee and tea 24/7 which is a nice touch, as well computers and free internet for guests.
The T (Blue Line - Aquarium stop) is located right outside the door; changes to other lines can be made at Government Center just two stops away.
If you're attending an event at the Garden the walk from the hotel is 15 minutes - and be sure to stop in for a drink at The Fours - great bar/restaurant along the way.
Faneuil Hall is literally a five minute walk and the Aquarium is across the street. Boston is a walking city and if you're up for it in 30 minutes you can be strolling down Newbury Street.
The Black Rose Irish Pub is across from the hotel - tourist trap but in a pinch not bad for a quick bite and a drink. There are a number of other bars close to the hotel and on a Saturday night they are packed. The good news - you will hear absolutely no noise in your room from the streets below. And lastly, avoid breakfast at the Marriott Long Wharf - two people not much to eat and no cocktails $55.
Would we stay here again - yes!