I completed both story modes today, got through the majority of arcade mode, and have played with the online section (3 wins, 1 loss by the way).
It's a surprisingly good Mortal Kombat game, despite what critics have been saying. Having owned MK: Deception and two copies of Ultimate Mortal Kombat 3 in the past, I was ready to really hate the inclusion of DC characters and losing the majority of what makes MK what it is; gore, over the top humour etc. Turns out, the fighting system is so solid - truly the best Midway have made in years - that it's easy to look past what was lost.
The fighting system has turned into a more accessible Tekken, with each button assigned to a limb. There are two grab buttons, one being a traditional throw and the other is a new Klose Kombat system. Klose Kombat is nice but it can be frustrating in that it's simply Rock, Paper, Scissors and there's no real skill to it. It's a great way to mix up the fight regardless. Also, there's the Free Falling Kombat section, which works in the exact same way as Klose Kombat (Rock, Paper, Scissors with the buttons) except you're falling through the air, and Test Your Might, which comes back from MK 1. You basically run through a building while mashing buttons to up the damage percentage. I liked this new addition the least, as button mashing while you're in a strategic mindset is a bit too jarring.
The fighting seems to have been simplified, and most special moves are very easy to pull off. However, the AI can be ruthless, and juggling is constantly in play. It really does seem to take a lot of timing and skill to link together combos, and the DC characters are surprisingly fleshed out with many of them being more complex than the age old MK guys. However, there's also a new strategy in play called Rage. If you take a lot of damage through a fight, a rage meter fills and you can either use this to deploy a combo breaker with a single button press, or go into Rage mode. During Rage, your reaction animations to hits are turned off and you deal double damage. This can lead to many tense matches as you watch your opponent's Rage meter rise as you pummel them, and can be frustrating when it's used against you, but it's a very cool system that can be used to your advantage if you learn how.
Story mode is fine, and is suitably ridiculous. Dialogue seems to be proudly idiotic, and the DC guys act like they're inside a '70s comic with out-loud monologues and their own individual quirks fully intact. Once you finish the story from both MK and DC sides, however, you're probably never going to go back, and I saw it more as an introduction to each character so you can feel out which one is best for you.
Arcade mode is fully intact and is the same as it always was. Nothing to report. Online is very interesting in that it's like a late '90s chat room. You enter rooms and see a list of people who are talking through text or voice, and can challenge whoever you want after looking at stats of their experience. This is a pretty good way to match yourself up with people of equal skill, and I really like it. If you don't want to use the chat room, you can just let the game pair you with someone automatically with the usual ranked/player match types available. Lag is near non-existent, depending on who you're fighting, and it all works beautifully.
In conclusion, I really like what this MK has done. It hearkens back to a simpler time of arcade fighters with its presentation and classic arcade mode. It even has an attract mode when the controller is left alone, and the fighting system feels fresh, modern but also similar to what has gone before. However, there's not much to the game, so if you're not the competitive type, you'll lose interest fast after story mode is over. For those who love to dip into fighting games though, this is a great game and is accessible enough that you'll never feel intimidated by the game, and you really do want to learn how to fight better, unlike many other fighters these days who have gone so crazy with complexity that they're simply imposing monsters to any newcomers.
I'm sorry if I went on too long, or the writing is poor. I'm on painkillers for a raging headache and have a cold coming on, but I'll answer any questions.