Yeah, it's cool-down based, very similar to WoW. Though it has a double cooldown, making your moves stronger or dealing special effects, so it's up to you to decide if you wait for it to recharge another time or use it on the first cooldown. Also if you could charge a "TP" counter (that's its name in the game) you can use that points to make special "TP" attacks, or wait until you fully charge it to enter into a "overdrive" mode, when your attacks recharge faster and you can wait until a third cooldown to deal more damage. It's similar to MMORPG's battle system, but more complex. 

And yeah, your members are controlled by the AI. You can customize their arts, and "Soul Voices" though. And yeah, there are 8 classes, but you can identify tank, healer and damage dealers, but it's a tad more complex than that. Characters have a predefined role, but you can take whatever role you want in the party, and change it whenever you want. You don't have your mecha maybe in the first 20/30 hours, but after that it feels necessary to take down some monsters, so I'd say it's very dependant after you can achieve it. 

I was afraid at first because it is very complex, but now I love it. Even today, 35hrs after, I'm still discovering many things of the combat system like the TP system.

I was excited to try for the first time, and it pay very well.

But... many didn't like it and I'm not surprised, it is a combat system that not everyone will like it.

MMO-style real time combat with a Chrono Trigger influence -- considering the key here is to stack the effects of your party's arts together. You can also target appendages for combat advantages and special loot drops - sort of like Monster Hunter.

I'm enjoying it a lot - and I don't even have the Skell yet...

Though I wish giving party commands and targeting changes was easier -- they could have used the touchscreen for this.

Yeah i found trageting appendages to be a pain in the ass aswell but then i discovered that you can lock on to them and i felt like an idiot. I only use the party commands for focus fire and enter/leave their skells. I completely agree that they could´ve made something with the touchscreen during battle since it doesn´t do/show anything during combat.

Honestly i'm just glad they're trying something new with this game.

How can you not like mechs!? :O

Honestly, I think they're a dumb design.  The humanoid type, I mean.  I'm completely fine with the Mechwarrior type.  The human body is a pretty awful design for combat and would get slaughtered by more logical designs.  Most Japanese designs turn me off completely.  In my opinion, they generally seem goofy and more suited to Power Rangers type shows.

It's addictive.

I don't like that all functions are selectable on a straight line, but other than that, it's very good. Pacing is great and the soul voices feature makes the battle dynamic and adds a layer of strategy.

It's fantastic. There is so much to mess with and to customize to make the battle system so different every time you play