Only hardcore players need apply
I'll put this at the beginning since it's important: you need a high level of Japanese comprehension -or- you need to be willing to be patient to really learn complex gameplay mechanics.
I, personally, don't have much knowledge of Japanese above gana/kana (I don't understand the story >.>), but the gameplay is amazing and complex. There's a number of meters to keep track of (Break, SP, AP), using the link system to bring over characters from across the field for combo attacks (or to get them out of being surrounded!), figuring out the synthesis shop (wish I could read more...), and a host of other things outside of battle and the fine balance/interaction between them!
I really love this game (I enjoy numbers SO MUCH that I don't need to have a story... though I wish I did). ...If the above statement sounds absurd to you, you might not want to get this.
Even if you do understand Japanese very well, I'd like to point out that game is HARD in addition to complex. The game has told me (many times) before that my characters weren't placed right... by killing 3 of them in one turn.
If you have a PS3 (and the hardness/complexity sounds fun), you may want to wait until the English version comes out soon.
Take a good long thought about this if it sounds good though, it'll really eat up your time! (in the good way ^_^)