Instead of write a formal review of the game, I thought it would be more beneficial to briefly explain the battle system since I know lots of folks have struggled immensely in the beginning stages of the game, even seasoned Agarest veterans. It's taken me days of experimenting and menu poking to finally distill all my understanding into a single passage that I think sums up the hardest part of the game: the beginning. Once you grasp this part, the rest comes naturally.
First thing's first: put the manual down. I appreciate its numerous, information-packed pages, but it is far too unclear and confusing, its ambiguity only exacerbated by wanting in-game instructions that aren't integrated as contextually as they should be. What's a spirit vessel to do? Well, If you're determined to play this game (or still on the fence about buying it), then hopefully this brief explanation will help clear up some things.
The battle system is only superficially similar to previous Agarest games, in that skill and combo names do not change and skill types and attributes are identical as well (for example, Black Mist is still a Dark Art). Gone are the in-battle menus where you select and combine your skills in "real time" into combos or single devastating attacks. Instead, all the choosing and tweaking occur outside (i.e. before) the battle screen, in the main menu screen, and it's up to you to remember which attacks will occur at what times.
And while many of the skills from previous games exist here (e.g. Power Attack, Black Mist, and in Agarest 2 they are called Active Skills), each attack is assigned a button on the controller and an associated "state." Triangle for "Up" (as in a launching attack), square for "Stun," X for "Down" (as in grounding an opponent), and circle for "Ranged." Each state is allowed to have equipped three Active Skills (again, e.g. Power Attack, Black Mist). During the very beginning stages of the game, this is all you need to know so you can get a feeling for the new layout, but as you progress you will desire something more, as in combos.
To explain combos we need to elaborate on Active Skills. Each Active Skill is associated with a certain number the game refers to as "Commission Skill," and this number will display on the far right of the Skill menu screen, in a long vertical box. For example, if you add Earth Spike to an Active Skill slot, a number in the Commission Skill box next to its associated element (in this case, earth) will appear. If your previous number under earth was 0 it will increase to 1; and the more earth-type attacks you add the higher the number will become, or the higher your Commission Skill will be.
Let's set all this to an example. Sonic Blast is one of the earliest combos you'll be able to perform, let's say between Weiss and Victoria, and is activated by two successive Stun attacks. First of all, equip the Combination Skill to a character, say Weiss. You'll notice that it requires a power Commission Skill level of 1 for one character and level 2 for the second character. To get to level 1, simply add an Active Skill that will do the job, in this case Power Attack.
Although Weiss has the Combination Skill Sonic Blast equipped he still needs a partner, but Victoria's power Commission Skill level is 0. Each Combination Skill has requisites for initiation, and in this case the second character needs a power Commission Skill level of 2. To get there, simply add Active Skills of the power type to Victoria.
To perform the Combination Skill, you have to use Stun attacks on the enemy with Victoria until the AP gauge (the circular gauge at the upper left) is 1/3 full, at which point you should switch to Weiss, who together with Victoria performs Sonic Blast.
But how do you acquire skills? By way of Skill Books, which you can "equip" by navigating the "Learned Skills" tab (again in the Skills menu), where is displayed yet another tab called "Unequipped." It is here where you will learn new skills from Skill Books.
Skill Books can be purchased with TP from the Training Grounds (Righteous Beheading, which is accessed by completing a certain number of commissions from the Hunter's Guild) and any character can access a book via the aforementioned menus. However, it gets confusing because the books are color coded and grouped accordingly, and a character can only learn skills from one book among its associated color group. For example, Beginning Arts 1, 2, and 3 are all teal, so if Weiss learns from Book 2, he will be unable to learn from Books 1 and 3; he is locked out. Once a book is assigned, or equipped, to a character additional TP must be spent towards the "learning" of its associated Active Skills, and once all skills have been learned the character will have "mastered" the book and the book will then become available to another character to learn from. And just as a character learns Active Skills, he too learns whatever Combination Skills are associated with that book. You can probably see where this will eventually go. Certain books will be better suited to certain characters so it's wise to match Active Skills accordingly, which leads to more appropriate combos.
One more thing on combat. Enemy weaknesses have always been a vague nature in the series yet Agarest 2 states it clearly on screen. However, with the added attributes of Up, Stun, Down, and Ranged things get slightly more complicated, but it's actually really easy. Simply keep in mind that the higher the percentage the more susceptible to that type of attack the enemy will be. For example, an enemy with 85% Up, 100% Stun, and 125% Down will fare less fortunately (for him) against the Down attack. In other words, he is 125% more susceptible to Down attacks.
All this, of course, isn't everything to combat, but I only wanted to discuss the more confusing elements, since the remaining aspects are fairly straightforward and explained well enough in the game. Things like Extended Area, Ultimate Strikes, and so forth aren't too hard to grasp. One thing to keep in mind, though, is that you really want to complete commissions in the Hunter's Guild (they're basically side quests) because you'll be rewarded access to higher levels of skill books as you complete certain quests. This is vital as you progress through the game, as enemies become stronger and simply leveling up and upgrading equipment won't cut the mustard. Another pointer is that you want to play to your party's strengths by learning books that play to each character's strengths, as doing so will result in a stronger team. For example, in generation 2 I've been learning roughly the same two types of attacks for Schwarz and Jude (Power and Combo), and the results have been really good. My physical damage combos are for my melee characters while my magic combos are reserved for anyone with good intelligent stats, since it seems combos that use both melee and magic characters yield inconsistent damage. This is a good way to split the way in which you assign skills and combos to characters, and you can create multiple teams that have different strengths. This is a pretty cool level of customization, I would say, that goes further than the previous two games.