BWI is probably my favorite Disney resort (right now).
As others have said, the location is fantastic. Not just the walk/boat ride to Epcot & DHS, but also having all the other Epcot resorts in walking distance -- your dining & shopping options are unbeatable.
The atmosphere on the boardwalk is lively & fun. You really feel like you're IN Disney -- the energy of the parks is there. It's not a stressful energy at all, though. It's nice just to sit on a bench and watch the boats go by, watch kids kicking a ball around (seems there are always kids playing in the grassy area), watch the entertainment. It's great.
The rooms are really lovely. Without a doubt my favorite Disney resort rooms. They actually look & feel "deluxe." We stayed in a standard CL room and overlooked the back courtyard. It was so pretty and peaceful, and we could watch the fireworks from our balcony.
Finally, the CMs there are outstanding. Every one we encountered there was so friendly and helpful. Every. One. CL staff, housekeeping, groundskeepers, bus drivers -- they were all SO outgoing. My husband was even like, "How is it possible that every single person here is so nice? Like, they didn't manage to hire even one jerk?" HA!
In the interest of fairness, a couple of negatives. One, I found the walls to be rather thin. We could hear people walking down the hall & hear the water/shower/toilets in other rooms. We've never noticed that at other Disney resorts.

And two, pretty much all the shopping & dining options are out on the boardwalk, so you do have to go outside to access them. A real bummer if the weather's bad.