You will love the Dolphin. I have stayed there on several occasions when I wasn't able to book BWV!! I love the area..so easy to get to both Epcot and DHS. The one thing you have to keep in mind is that you can't use DME..you have to use the Mears shuttle, rent a car, or use a car service. And, you can't charge purchases back to your room if you are off Dolphin property. But you can have purchases sent to the front of the park and then you can grab it on your way out.
You can't add the dining plan at the Dolphin either...but that's not a big deal. The do have their own dining plan there, but I think it's fairly expensive.
The pool is terrific..one of my favorites. I love eating at Picabu...bottom level of the Dolphin. Great food there.
The park buses will also stop at the BW as well as the Swan and the Dolphin. And sometimes, YC/BC are also incuded, but not all the time.