The game is fantastic. It's basically what FFXII should have been. Not that I didn't like FFXII, b/c I'm one of the few people who really liked it, but nevertheless, there's something about LO that feels more like a FF game than FFXII did or XIII will, and it's not just the traditional combat system.
I love the difficulty, it was a huge surprise, although at a couple points it gets frustrating(I hate regular enemies that take 0 damage from regular attacks(SPOILER)like the ones in Kaim and Sarah's old house they burn through my mp so friggin fast)
I was excited about the 4 discs until I had to change to disc 2 less than 10 hours into the game. I thought the game was going to be huge, but I guess it's just average. I hope, though, that the the last disc is jam-packed full of extra stuff to do. I'm especially hoping for some massive hidden boss monsters.
He made it exclusively for 360 b/c Microsoft funded the development of Mistwalker. I don't think it has anything to do with anything but that.