Our family thinks the POTC at DLR is way better than the one at WDW. FOr starters, you start off high up (2nd floor) of a building. You go through the Blue Bayou area -- a huge Southern swampy area with crickets, fireflies, swamp homes and banjos playing. There is a riverside "mansion" on one side and they are having a dinner party out on the patio under colored lanterns. That is actually the Blue Bayou Restaurant and you can really eat there. It is so cool!
Then you go down one big (but not huge) slide and are warned about pirates lurking ahead. Then there is another slide (a little smaller, more like the one at WDW) and you can see and hear the pirates.
The way you enter just sets the stage so much better. There are also more rooms, bigger areas and the whole "burning town/burning ship" thing that the boats go under in DLR. Then you get to ride the boat back up to the beginning.
We are always happy to see the pirates in WDW, but also a little disappointed in the experience.
WDW has a better Splash Mountain, however. I think it just makes things interesting at both parks that there are these differences.