The battle system is both different and the same. I'd actually put it as more complex than Agarest 1 and Zero's, as there are more factors you must consider. In 1 and Zero end-game battles consist of knowing how to place yourself while staying within attack/link range of each other while also staying far enough away that not everyone is wiped out by AOE attacks. In 2 you have attack heights and types, wait times, SP (which not only is used in skills, but also for group attacks), as well as 1 and Zero's character placement and AP balance.
If you've played Cross Edge, you'll find it more similar to that. If you haven't, well. . .it uses the same AP style combos, breaks/shields, overkills, and so on, as earlier Agarest games, but rather than having a SRPG-style map, the map is instead split into two smaller grids that are used for enemy and character placement and determine AOE range. It's a bit hard to describe in words to someone who hasn't played it, especially because map nuances don't always become clear when you first play the game. I didn't understand a lot of it until quite some time in.
I tend to prefer the more traditional SRPG style of 1 and Zero myself, but the game overall in 2 is superior.