In the context of video game movies, Mortal Kombat is not awful. That is to say, it isn't horrifically wrong. It is, however, painfully average. Every story beat marches into its rightful place like a well trained soldier. The fatal flaw is in the protagonist, an original character for the movie. Cole (Lewis Tan) is dull and completely inconsequential to the movie. Why oh why is the mortal Kombat movie not about Scorpion and Sub-Zero? I haven't even played the games and I know they are the guys everyone cares about.
The gore is enjoyable, particularly for a 15 certificate and the hat guy was pretty awesome. But really there's plenty of other gory films out there which are much more enjoyable.