@viciousreiven: So the core combat is similar to a lot of melee combat games. You have a lot of preset strings that you can preform to do moves with a bunch that are unlockable. These move strings are dependent on both the character and weapon you have active. So where it gets interesting is you can mid-combo change either your weapon or your partner on the fly. There is actually a specific system in the game that rewards you with a powerful finishing move if you tag in your partner on the last hit of a string.
Each character has two weapons and a sub-weapon (or in the case of Saki a parry) now stack all of this up with the fact that in a lot of missions you can have all four girls with you meaning any combination of 4 characters and 12 weapons are at your disposal at any given time. There are other things like the "Cool Combo" system that reward caclulated entry of combos rather than mashing combos out. If you time combos correctly you'll start flashing blue this lets you know you're doing what is called a "Cool Combo" time the rest of the string properly and you'll be doing way more damage and also in some cases score bonus hits in the combo string.
There is also a weird assist character function where you can have up to all four girls on the screen at once attacking in sync with the character you're currently controlling. Its also just super responsive. You can interrupt moves with dodges at ANY time on the ground or air and actually Saki has a specific function I think unique to her similar to Bayonetta's witch time where if you dodge something at the last moment you'll get a slo-mo shot of her dodging followed up by the ability to counter attack for massive damage.
I can't lie and say that some aspects aren't still laden with fanservice because there is and a lot of the stages and enemy models have pretty shitty textures that remind you that "Hey, this is a budget game" but if you're really into just having fun with combat systems and can either not let the more poorly produced elements of the game detract from your overall experience you'll most likely have fun.
I should also mention that even with like 100 zombies on screen the game seems to hold up at damn near 60fps the entire time which is nice. Not trying to say this going to shake up the beat em' up genre or anything but if you've been wanting a decent one of these sort of games for awhile at $40 on PSN I think you can't really go wrong with this.