Just a great place to stay
Me and a friend visited Boston over 5 nights and picked the Millennium Bostonian because of its location. Most important that it was close to the TD Garden.
The only hiccup during our stay was when we arrived, however that did not take too long and the staff was very helpful (which was good since we had a looong trip behind us). During the stay, staff was always friendly and helpful. Not over the top-friendly just very pleasant and nice.
The room was great, really tidy and clean (like we found it to be every day when we got back, cleaning was GREAT). Bed was a little too soft for my liking but that won’t take away from the whole experience. A lot of TV-channels however the quality was really bad, especially on some channels. Digital TV should be considered. 
The gym had what you need but could have been a little bit bigger perhaps. The mini-bar was nice, but I actually like to put my own things in there so I never like a stuffed fridge. I want certain sodas/beers/wines/snacks etc.
The location was great, not only close to the Garden but close to everything it seemed. Traffic outside did not disturb us at all we slept really good. Its close to a lot of sights and easy to find a T-station with different lines.
Overall a great stay, I don’t know if the price is that good but we felt we got our money’s worth.