I have to say I like the DDs, find them very comfortable and they're nice enough place to sit. No Mark III but the ride is decent. The Cork coaches are pretty awful though, seats are poor/hard, the ride is poor too, the feel like they hunt all over the place. Don't feel especially well made either. The ICRs are nicer, even with a engine under your feet.
The worst of all though currently is the 1st generation Japanese DART units. Feel like you're leaning on a window ledge than sitting down!