It was much more lifelike...
It took me a while to get used to it, because with random battles I always felt I was in control (esp FFX), the idea of pre-setting moves was a big hurdle to get over. But once I allowed myself to trust my gambits, and therefore my characters, it just seemed to click with me.
I really liked how much you could personalise the abilities of the characters, you can have them learn anything you want. And swapping weapons was a lot of fun- I had Fran running around like a maniac with a huge axe!!
I must admit I still love the random battles, but I think this is a good system in its own right.