Having watched some videos and read some reviews, the game appears to share several similarities with both of Mythic's aforementioned RvR innovators. Aika will feature quests, item crafting, gender-locked classes, and yes, large scale RvR including keep sieges. The publishers claim they can handle battles up to 1000 vs. 1000. That will be quite a feat considering the detailed graphics and animations.
That's about where the similarities seem to end though. Aika is an MMO of South Korean descent and definitely has the look and sound effects. The MMO will also be free to play (just how free, we don't know yet), boast sophisticated voice-overs, and come packaged in a tiny 300MB download. And then there's the interesting (some might say creepy) "Pran system." Prans are kind of like pets from traditional MMOs, except that they are young girls. According to one review, you can interact with your Pran, dress it up, give it dolls, help it grow, and boost its intimacy/relationship rank.