I havent played Grandia Xtreme as it wasnt released here in UK, and I didnt import as, well it wasnt very good. Grandia I+II were great, sure Grandia II isnt what Grandia I was, but it was very entertaining, and I loved the Plot. Grandia I is one of my favourite RPG's ever. Lets just say that.
Only thing I dislike is how characters are here and there in your party, and You'd need a walkthrough to know when they would leave, as You could spend all your time training a character, then they just leave on you.
Still, Grandia is a very good, but thus, very underrated series, hopefully Grandia III will change that :)