My family of five (DD13, DS10, and DS5) have stayed at that hotel many times over the past few years. We do really enjoy it and have mostly positive things to say. First, the price for an oversized family isn't cheap, but is not overwhelming. I stay at Embassy Suites hotels a lot in other cities too and like the brand. The free breakfast is ample and a good way to start the day. We haven't had too much trouble with this in Anaheim, but Embassy Suites design and floor plan can lend itself to noise issues occasionally.
Going to DLR, you can catch the ART shuttle at the hotel. I won't lie - the shuttle can be irritating. For one thing, a LOT of people take the shuttle from ES. My advice there is to try to stay ahead of the crowd - get on the earliest shuttle to get to the parks (that will help you in the parks anyway) and realize it might be a crowded ride home after you are done at the parks.
Tell me the good the bad and the ugly about the Embassy Inn Suites South! We are going to visit the Mouse April 29th - May 2nd. 
