Competitive Mortal Kombat at its best.
My difficulty rating of "Very Hard" is because the game is designed to be played against another person, and not the AI. The AI is poorly programmed in the sense, you cannot actually fight them, you have to trick them and figure out the AI patterns which are extremely simple, and many are universal. There are methods for defeating every character in the game which are fool proof, so that would make the game "very easy," however, playing another person and becoming good at this game is not. It takes years to master the mechanics of this game, which is why there are still people who play it.
If you are nostalgic, like MK in general but never tried it, or are just looking for a game to pick up, I would suggest UMK3, and finding others who play it. There are still arcade units for this all over the country, and tournaments run on a regular basis.
To learn more about this game, visit www.ultimatemk.com/forum and receive tips from professional Mortal Kombat players.