DDR Freak posted this on their website:
The producer of DDR Ultramix for Xbox has taken the time to post in the forums to clear up some details about the game:
1) The Look of the game at E3 is not representative of final game play. In that version we had no 3D, no Music Videos and haven't even begun to show what the Xbox is capable of. I promise you this game will be the best looking DDR game out there. So expect everything to be updated. We are not taking any steps back and expect some very cool looking characters!!!
2) Freeze Arrows - Yes we will support Freeze arrows but none were present at E3.
3) Online - Yes we will have player vs. player internet competitions with Xbox live rankings and statistics. Your individual scores will also be able to be ranked with the rest of the people via the Live connection. User edited step data will also be available for upload and download by users. New songs will be released on a monthly basis for download.
4) Song List - The songs we had at E3 are available to be used on the final version. We have 55 songs planned for the US version (10 licensed)
5) There is no ULTRAMIX PC version.