We flew into Dulles and stayed here for a few nights. The shuttle between the airport and hotel runs every 30 minutes and was always right on time. The hotel was very nice. We were pleased with our room, and heard no noise from anything. The bed was very comfortable. Our room package came with Internet and breakfast. The breakfast buffet was outstanding. I don't know if you can book a room without the free breakfast, but if you can - watch out. The buffet regular price is $19. As fantastic as it was, it's not worth that. There is an indoor pool with hot tub and a nice looking fitness room. The pool area is functional - nothing fancy or romantic, especially with the life guard on duty, but the hotel can't help that - apparently it's state law.
There were only a few things that were not excellent. They did not detract from our stay, but offered just as constructive feedback for management. 1) My husband likes to sleep colder than I do. The bed covering/duvet was very lightweight - hardly more than a doubled sheet. There was no extra blanket in the closet which would have been nice for me as I got a little cold. 2) We ran out of kleenex the first few minutes we were in there - it obviously was not a new box - only a few tissues left. There was no replacement box in the room for us to use. When housekeeping came the next day, instead of replacing the empty one in its holder under the sink, they just left the new box on the counter and we had to crawl under the sink and replace it ourselves. We thought it was lazy and unprofessional. They also left used drinking glasses where we left them. When you've been gone all day sightseeing, you expect clean glasses as we don't remember who left their glass where. 3) The carpet was coming up in the hallway - you could see the seams and it didn't lay flat. Just something you don't expect to see in a nice hotel.
The hotel is not near a metro stop, nor are there any restaurants or shopping within walking distance. So, you are isolated, if that is a concern. It is at least 30 minutes away from downtown and the typical tourist sites. You could take a taxi to the metro station to get downtown. There is another Hyatt up the highway a couple of exits that is part of Reston Town Center with lots of shops/restaurants that might be a better choice if you want places to walk to. I don't know anything about that hotel itself.
Overall, if you have business in the area or want a hotel near the airport, I would recommend it.