The same as the PS1 version (NOT an emulation, don't misunderstand please) without the frustrating loading times, and to play as Chameleon you just gotta hold HP and LP instead of that six button combination that I can't remember right now... Btw, the Classic characters are unlocked with 7 on the NumPad, if you're player 1.
There's DualShock 4 support too, BUT try not to lose connection when the game is loaded, otherwise after you reconnect your DS4, you have to restart the game to be recognized again.
About the swapped music, it is almost fixed... almost because there are still some flaws: as an example, MK2 The Armory uses its theme! But MK2 Kombat Tomb uses The Armory song... BUT Kombat Tomb song is used in MK2 The Portal! What?? (also there are certain stages like MK1's Courtyard which use MK3 music, but I guess it's just game limitations since that MK1 song is not in the game. There's also no music at the end of the rounds, as always. Another game limitation, I guess)
Intro videos can't be skipped tho', ugh...
Anyway, if you're looking for the PS1 experience enhaced, then this is your version. It runs nice, and (of course) it's pretty fun.