Here's the issue with 3D on the DS: Everything is in focus on the screen. As I'm typing I'm only focused on the moniter, but if took an image in 3D with the 3DS it would have everything in focus. This confuses my brain, so instead of focusing on just part of the screen my eyes focus on the whole screen.
Dead or Alive Dimensions is awesome. It's also the first video game I've ever played that allows you the option to skip a cutscene, pause it, or restart it while watching it. It's quite nice.