I love the new fighting systems. I also think that the fighting systems get better as the games evolve.
I first started playing Mortal Kombat with Deadly Alliance and I finally picked up a classic MK game the other day (Mortal Kombat: Trilogy), and found it very difficult because I didn't know what the hell was going on because everything was moving so fast.
I like it in the later games how you actually had times to think about what move you were going to do next, as your opponent is not constantly flying at you with more moves.
As Asylum said in the previous post, I also think that air kombat is fantastic. I have finally gotten the hang of it with Fujin.