You can jump over someone and jump kick on the other side like MK2. You can do a downward punch that bounces off the ground. Jumps are rather short range. Some characters have air moves like Batman's battarang.

kitana has a little kombo that she can do with her box air attack.lyk in mk3.
there isnt that much besides that,its just hit downs and pop ups.
:D

It's closer to how it was in UMK3

Main difference is how the punch can either cause a stumble or a bound, depending on which button you use.