I'm glad Wii-volution sent in this interview with Dragon Ball Z Budokai Tenkaichi 3 producer Ryo Mito. It'll tell you a lot more about the additions to this game over the last one than I can.

I played this at the Atari booth at PAX, and while I didn't exactly know what was going on, I was really enjoying the game. I don't know how it compares to any previous Budokai games, but the Wii controls were really easy to use and had me executing crazy combos and chaining teleports and beam attacks and big punches all over the place. The special move inputs require you to hold a button and then make a motion similar to the actual move (a diagram of the required movement appears at the bottom of the screen.) I played as Nail, and had to cross my arms in front of my chest to do ... I don't know, some big flashy thing. I really dislike Dragon Ball Z, and I had an awesome time playing the demo.

One thing even I can tell you is new to the series, and totally amazingly awesome: it's online. I asked the Atari rep twice to be sure. Online.