Terrific Value, Modest Accommodations
I had read so many awful reviews of this hotel, but I decided to give it a try anyway and I'm so glad I did. It was recommended by the staff at the Boston Shriners Hospital. We only stayed 2 nights but it was perfect for us. Located in Charlestown, just across the river, patients and guests can catch the complimentary shuttle bus to Mass General. There's also a convenient stop at the North Station for the subway. 
We stayed in room 428. The rooms were average size and very clean (in fact no dust - which usually bothers me in hotels). Bedding was clean and fresh. We had a mini fridge and microwave in the room as well as a nice flat screen tv. The air conditioning worked perfectly. The bathroom sink was a little tiny but the shower was clean and hot water plentiful. 
This is a no-frills spot, but for our purposes and the cost (under $100/night), it was great. Staff was helpful and friendly. Safe location - my son and I walked back from the shuttle drop off at 10:30 at night and had no issues. 
G