This DoubleTree is comparable to a well decorated but older Holiday Inn or Clarion hotel.
We stayed in the DoubleTree on Rhode Island Avenue during the latter part of June 2012. Not a bad hotel but I expected more from a DoubleTree. There are some good points. The hotel is very nicely decorated. The breakfast buffet is quite good. The beds are clean and comfortable. The windows in our two rooms opened allowing fresh air circulation. The air conditioners, the LCD televisions and all the bathroom plumbing and plumbing controls worked well. The rooms have free safes and the WiFi functions as it should. The fitness center is quite nice. 
Other Trip Advisor commenters have complained about noise from adjoining guestrooms and also about the size of the rooms and bathrooms. Noise from within the hotel was not a problem for us. However, the dumpsters behind the hotel (about half the rooms face that direction) were emptied every weekday morning around 7 a.m. The guestrooms are indeed small. Think European in size. The bathrooms are tiny. Think Lilliputian in size. 
The entire hotel staff speaks heavily accented English. I had to ask some staff members to repeat themselves and sometimes they needed me to repeat myself. Occasionally, what they had to say was incorrect. The concierge told us the Washington Monument was open. We took a taxi to it only to find out it had been closed for a year and would remain closed for another year. While the breakfast buffet is nice, the rule that Hilton Honors gold/diamond members must pay for consuming hot breakfast items is strictly enforced.
Maintenance and cleanliness were less than perfect. The desk chair in one of our guestrooms not only had four or five obvious rips in it, it was missing a wheel making it unusable. I can’t imagine how a maid thought we wouldn’t notice that. Similarly, the bedside Sony clock/radio was obviously broken. The plastic casing was literally coming apart. In the bathroom of the same guest room, there was lots of hair on the floor and tub from a previous guest. (However, the bathroom in the other room was spotless.) In the first bathroom, the soap dish in the bathtub/shower was mounted at a tilt so nothing would stay on it. An electrical outlet we wanted to use did not work. The phones in both guestrooms were very dated, some buttons did not work and the wrong room number was printed on one of them. 
One of the three elevators was out-of-order. The sign on it saying so appeared to be permanent. Unfortunately, that elevator was needed in the mornings and late afternoons. The red carpet on the steps into the restaurant needed replacing. Many other things in the hotel also had a worn appearance.
This hotel is at least five blocks from a subway stop. However, there is a wonderful Whole Foods grocery store at 1440 P Street about 2 blocks away with an amazing deli inside. Actually, the deli is more like a restaurant with a large selection of very good food. There are even tables and chairs along the front of the store. It is a great, reasonably priced venue for lunch and breakfast. Additionally, there are some regular restaurants in the area but other than the hotel restaurant and the one in the adjacent Holiday Inn, the neighborhood restaurants are all at least 2.5 blocks away. 
The DoubleTree on Rhode Island Avenue is comparable to a well decorated but older Holiday Inn or Clarion hotel. That makes it a fine place to stay if you get a good rate. One Trip Advisor poster said he got a $100 rate on PriceLine. I checked PriceLine myself and without even using the bidding option found rooms at the DoubleTree for $147 per night plus tax and junk fees. I liked my stay at the DoubleTree but if I had paid more than $150 per room per night, I would have felt that the price/value equation was better elsewhere.