At "high levels" (ie. if you and your friends are nerds who play a lot, or troll online

) then yes, big differences in ease of use and damage characters are capable of.
For the best players, Kung Lao, Sub Zero, Ermac, Reptile, Cyrax and Raiden have been used to dominate the 3 fighting game tournaments that have been on in the U.S since Mortal Kombat was released. "Tom Brady" who won the first tournament and did some of the testing on the game before its release has said something about a balance patch, so hopefully a few more characters become legit threats. Right now Baraka, Sheeva, Noob and maybe Jax could all use a little help. But for different reasons. Baraka only has 1 or 2 combos, Sheeva is a bigger target and at the moment that makes Sheeva-only (opponent) combos possible. Terrible thing. Noob doesnt have much for the 25 characters with teleports and Jax is a bit slow. Everyone else is pretty good and has a fair chance against any opponent.
Street Fighter was a more balanced game but it had none of the single player content and unlockables that this game has. Although in truth most of them are artwork trash, who actually cares about unlocking that? But you can unlock 2nd costume and another fatality in the krypt which are more useful than the colour palette swaps and extra taunts in street fighter.