I stayed at the Swan last year, and am looking at staying at the Dolphin this fall. For me, the best thing is the location. It is wonderful to be able to walk/boat to both Epcot and the Disney Studios. And the cost is around what you would pay for a Disney moderate, much less than the Disney deluxe resorts that surround the boardwalk.
The minus for me are the lack of a typical Disney food court, and not being able to use Magical Express.
My experience was mixed. Again, loved the location and the ease of getting to Epcot. My room had a bit of a musty smell, and it worried me a bit as I have asthma. But I cranked the air up and sprayed some febreeze, and it took care of it. I had also asked for a down free room (due to allergies) and they couldn't confirm that it was down free, only that it was supposed to be down free. But my bedding was no different from that in my sister's room, so that made me a bit uncomfortable.