I've beaten quite a few times. Its ending is a little too fairy tale for me though.

I have problems with my disc as well since I got a small scratch on the 3rd disc that appears during a simple cutscene that lasts a minute. Due to the scratch it now takes 20 minutes... Throw in the fact I felt the cutscene in question is a bit unnecessary (SPOILER)(its the one where the pillar places itself over the Lunar Point) and you can see why I've been a bit hesitant to play.

X is the easiest to complete. Yeah the extra challenges are hard but they are completely optional and hold no benefits gameplay or storywise except for bragging rights. The main story is pathetically easy.