Putting comic book heroes and villains in a MK game doesn't make it any better. In fact, MK vs. DC takes some steps back
The game has some really awesome graphics for the Kombatants. It seems like they spent more time on the fabrics that the characters' outfits are made out of than they did the characters' faces, but for a Mortal Kombat game, its very detailed in that respect. The gameplay is fairly straight-forward: punch buttons, kick buttons, throw button, etc. There is a new "Klose-up" mode that is interesting, although almost pointless since the AI almost always counters one of your 4 hits you can get on your opponent. The falling Kombat is similar to Klose-up combat… except, obviously, you're falling. And you get a special move when you raised the meter enough. Hmm… this seems to be the end of the positive things about MK vs DC. Let's look at the downside, shall we?
I mentioned the graphics above, but what I left out was the bland stage environments. Street Fighter II has better fighting stages than MK vs DC. They aren't graphically up to par with the character models, that's for sure. And speaking of the models, it seems that some characters' motion capture models were mannequins… most notably Wonder Woman. Her fighting stance is so stiff, you wonder if this woman will be able to defend herself properly. Some characters fighting moves were not very creative. (The Flash… run and punch is basically all his special moves.) Unfortunately, these are also the ones that are frustratingly cheap. And for all of the characters in both the DC universe and MK universe, they had to add useless characters like DeathStroke, Captain Marvel (??? why is all I ask…), Baraka, Jax… and I'm not particularly fond of Lex Luthor either, but I understand why he's in the game. Also, you only get about 18 playable characters… a far cry from the amount of playable characters in MK: Armageddon. There is not a Krypt for extras and no alternate outfits for the characters. So once you play through the story mode for each side, you've pretty much completed all you need to complete. The arcade endings are a waste… just one single image while the "narrator" describes the ending. And the story mode storyline is very dry. Two worlds merging… the MKs think DCs are the enemy and vise versa. Their fighting makes the merge progress quicker. Boring.
If you're an MK fan, I hear there's a real, stand-alone MK in the works. Save your money for that and just rent this. Its worth playing through once, but after that, you'll put it down for something else you play on a regular basis.