The good, the bad and the ugly...
First, the good. The location is second to none. It is a 2-3 minute walk to the aquarium, Faneuil Hall, Quincy Market and boating tours, a meager 30 steps separates the front lobby from the Aquarium Blue Line T-stop and the North End and it's amazing restaurants is only 10 minutes away on foot. There is a quaint hotel bar on the 1st floor (which is actually the 2nd floor) and they have music, performances and presentations most nights of the week in the adjacent counting room. The bartender, David, was a delight, accommodating and a joy to chat with.
The bad. When we checked in, our floor carpeting was completely soaked for the 1st 24 hours. Shampooing the carpet? Let's hope so but it was quite uncomfortable. The kitchen facilities in the room are next to non existent. Microwave, mini fridge and sink. Dishes and utensils are included in the room as well as a small table but God knows why. We had use for coffee mugs and that's about it. 
When booking the room via vacation club, we inquired into pool facilities since we were bring our 9 and 6 year olds. We were told the Custom House did not have a pool but an adjacent Marriott property did and we could use their facility. Upon arrival, we were told Custom House guests had not had pool privileges in 8 months!! Thanks for the heads up. Our kids were disappointed. 
One evening, we called the front desk and asked for a 7AM wake up call. Three days and one non refundable excursion that we missed later, still waiting for that 7AM wake up call. 
Do not disturb signs are more of a guideline and not a rule. One morning, the maid helped herself right in even tho the do not disturb sign was clearly posted. Next day, instead of coming in, she knocked on the door (do not disturb sign clearly posted again) and demanded I exchange out towels with her and bring her the trash cans. Now, I'm all for fresh towels and clean trash but, really?
The final night, we called and asked for a late checkout. We were told, "That will be difficult. You know, no. Can't do it.". So, down I go, rehash the trials and tribulations of the past five days and were given an extra hour and a free continental breakfast. Gee, thanks. That's right, even the yogurt and Danishes cost money...
The ugly. It is LOUD. We were on the 18th floor and could hear the homeless ( who swarm the place and pester you for money) screaming and cursing into the wee hours of the morning. The sirens are a constant. If quiet nights for sleeping are your primary goal, this place might not be for you. 
Ultimately, as a vacation club member, I understand their space and amenities are limited but we pay good money for quality accommodations and I think the Custom House, for whatever reason. Is lacking. 
Will we go back next time in Boston? I really don't know...