Whenever Dan appears in a Street Fighter game, you can bet that he's going to be way underpowered and tough to use, which makes him quite the challenge to get good with.

Take his "ultimate" maneuver, for example. So if you're playing as him and you get the Hyper Combo gauge up to maximum (L. 3) and you press:

Hard Punch, Light Kick, Back, Light Punch, Light Punch

He moves in for the kill!

Except that when he's done, his opponent loses very little energy, and Dan loses almost all of his!

So why would you ever want to do it?

My best guess is that you'd use it to show off as you're beating someone senseless with Dan. But, since he's kind of hard to master, I've never actually been able to prove that.