Konami kinda threw the DDR vets a bone. There's a song on there called Pipe Pop that apparently takes samples from Make a Jam (from DDR 2nd Mix) and Funk Boogie (DDR Extreme PS2 US).
Back to the subject at hand, man I gotta give this game some credit. It's got some great music, and the Super Hard stepcharts I've ran into are really fun to do and actually have a good flow to them. I would say that most of them would qualify as a 7 or 8, but a couple of songs like the Bowser song do tread into the 9 foot mold.
I would say the only real thing that needs improvement here is to add freeze arrows and put in some more songs, maybe some Konami originals outside the Mario world even. I mean, the US Disney Mix did it and there was no problem at all. Other than that, it's like 1st mix all over again and that's not a bad thing considering that most people who will be playing this will come in completely new. It's plenty enough for those just starting and it's pretty good for moderate players. However, if you're one of those OMG I AAA'd Paranoia Survivor Max Oni people, go back to In the Groove.
On a slightly unrelated note, I know U1-Asami did some of the music in this game (he HAD to have done Pipe Pop) but I'm wondering who else did some of the others. I'm not completely sure, but I swear I heard some Naoki and DJ Taka in that songlist.