In the first game when you let go of one of the keys, you would slide a little bit before stopping. This meant you could move around easily with just a few taps.
The one thing I'm having an incredibly hard time coping with is the fact that sliding is gone from Ultra. When I wanna move, I have to keep that key held down all the time. I even noticed my wrist getting sore. I relied in that mechanic heavily in the first one. It was just my play style. I would tap/slide around a lot.
I just wish there was some way to get that mechanic into the 2nd game. :/