i personally dont even consider it a sequel. It was more of Yunies miscellaneous adventures and a poor excuse for a "love" story tied to it. I was kind of mad that i wasted my time trying to find tidus when all i got was Shuyin and the notso good ending. It wasnt until i found out that i CAN get tidus back, before i picked the controller back up.
IMO, they should have either (a) left it alone at the end of x where you see tidus coming out of the water. Because that was good enough for me. A slight hope that they had let him out of the far plane to be woth yunie or (b) make x2 about yunie going to the farplane with her new crew to go get her man.