Definitely not normal Marriott quality
Very big complex which knocks this hotel down several grades. We were there recently for a 3 night stay to attend a conference at this location. The room we were forced to take was in the Park Tower. This is the back end of the hotel and apparently dug into the hillside as you are more or less in the basement. The room would have been good for a Super 8, but I was staying at a Marriott and expected much better. The whole complex is aged and we have a couple of issues with our room which took multiple calls to the front desk to resolve. I can not really speak specifically to value as our room was paid for by work, but I know what the rate was and I would not call it any sort of value for the price and what our accomodations were. 
I do not know the DC area and can't really speak to the location with much authority. It seemed to be in an okay location, the zoo nearby, we walked about 2 miles to J. Pauls in the Georgetown area and the Metro is vey close which we took for about a 1/2 hour ride to a Nationals game. 
I would not stay here again unless I was on a free ride.