Just played this game (in 3D, it has _awesome_ 3D) for 6 hours straight yesterday. I barely ever do that anymore. This is how a fighting game should be done. Story mode is amazing. The fighting system is absolutely fantastic with its depth and gameplay. The graphics are absolutely amazing. I've been learning each characters combos etc., been training quite a bit as Kratos (such an awesome addition to Mortal Kombat). Really looking forward to getting into King of the Hill online. Also plan on trying to get through most of the 300 challenges.
The amount of content in this game is just fantastic. Tekken, Street Fighter, Marvel vs Capcom; this is how you do a fighting game from a content point of view. It's not enough anymore to just have an "arcade mode" and some challenges. Tekken and Soul Calibur are two fighting games that add a little bit, but not nearly enough.
Fighting combat system aside, the bar has been raised in the SP and MP modes of what a fighting game should contain and the quality.
Love everything about it. Mortal Kombat is back!