Rhythm Thief & the Emperor's Treasure is near the top of my list of wanted 3DS games. I didn't write our preview of the game at TGS, but I did make time to play it, and I'm certain that it's going to be great.
This new trailer from Sega shows a lot of gameplay. I only got to play the song that you'll hear at 1:45, but know that there's a lot more to that song than what you see here. It transitions after a bit, picking up the pace and the fun. From the looks of this trailer, they've got a lot more tricks like that up their sleeves.
The second half of the trailer focuses on the game's animated cutscenes. It seems like they have an epic story lined up for us.