Its location on a map doesn't matter. DME is only for Disney owned-and-operated resorts. Swolfin aren't Disney owned-and-operated resorts, so guests at either one can't use DME. Same with Shades of Green and all the places on Hotel Plaza Boulevard (near DTD).
While it is "on property" it isn't a WDW Resort and dosen't participate in the Magical Express program, so you will have to make other arrangements to and from the airport.
You can however use Disney Transportation to and from the parks, water parks and DTD, in fact you can walk to Epcot and MGM if you wish. You can participate in EMH and have park purchases shipped to the resort. There is a WDW Guest services in the lobby so you can make ADRs and purchase park tickets, get maps, park hours, firworks times and such. There is also a Disney gift shop
Off hand the only WDW Resort perks I can think of that you won't have at the Dolphin are ME, the ability to have your admission on your room key or charge park purchases and meals to your resort room key.
However - IMHO the pro's definately outweigh the con's when it comes to the Dolphin.
There are a few Dolphin FAQ threads on the resorts board if you would like more information.