I'm currently staying here, so I will update again with my experience, but this is my third stay.
The first time I stayed, I wasn't even gold, but got upgraded to a club floor room (but the room was otherwise same size), simply because it was during the hurricane Irene and they just want to be nice (huh, no idea what hurricane has to do with it, but sure I'll take it).
The second time I stayed, I was not gold but have the amex card, and I got polite greetings acknowledging my card etc, but nothing concrete, and no club floor. This time I booked the deluxe room, but found that it's not much bigger than the regular room, so on my third stay I went back to regular room.
What I love about this hotel the most is that it's got indoor connection to Prudential Center, an upscale shopping mall that connects to Copley Palace (and even more upscale mall). This is so convenient in the winter time. Also, usually prices are expensive, but if you find it during low season, or with certain promos, it can go down significantly. I've had a double bed room (sleeps 4) for $130, in the heart of Boston. Can't beat that price.
The swimming pool is too shallow to do serious laps, and there are people making out in the corner usually, but the gym has the modern equipments and the sauna was a nice addition.
Everything else about the hotel is pretty standard. Clean rooms, small rooms and bathrooms but okay, standard Shine amenities. Parking is atrocious. I forget how much exactly but they charge a ridiculous amount for valet parking, and there's not much else you can do otherwise. This is downtown Boston after all.