I've gotten hold of the Blue Dragon demo on my XBox 360, and I'm rather fond of the battle system. It has a very interesting tradeoff between taking damage and dealing damage, which I like a lot because I think it adds quite the amount of strategy to your planning, and most certainly tests your timing skills as well. There's also an interesting field skill that allows you to instantly kill weak enemies you've killed before! Big plus for saving time when you just want to rush through a dungeon! According to the mini-tutorial in the demo, there's even a skill that allows you to stun the enemies on the field.
I've always found field manipulation interesting, and probably one of the many reasons why I liked Xenosaga. The notions of their shadows attacking is also an interesting one, since they all have rather interesting forms and some of them are pretty cute. :P
While I still don't know how worthwhile it is to acquire Blue Dragon, I think it's a pretty safe bet that it'll be a good game. I've begun putting quite the emphasis on RPG storyline compared to gameplay, because in my opinion, an RPG is for both. You want to see the storyline, while having fun stuff to do while furthering the storyline. (Yes, I find both lacking in FF12. My opinion of FF12 is beyond low since I find playing that game is sheer torture. You don't hear that coming from someone who played the four .hack games to the end very often, I'm certain.)
I'm highly interested in battle systems that place a tradeoff between damage and something else. To this extent, I am very fond of the battle systems in Grandia 2 and 3. I am unsure if I'll be happy with Blue Dragon's form of trading off damage for flexibility, but I think it'd make for a interesting strategic game. (Not difficult to see why I like Disgaea huh.)
One thing I find pretty interesting is the rather large party in the demo. Having 5 characters in a battle takes away some of the strategy that goes into planning your party since it's pretty straightforward isn't it? Three frontline tanks, one support mage, and another offensive mage.