It's only the best JRPG ever made...
My opinion :
Xenogears has so many flaws... Half the battles are so damn repetitive, exploration can be extremely tedious, there isn't much in the character customization department, menus suck, controls and camera angles suck...
HOWEVER. The music is absolutely beautiful (same guy who composed the Chrono Trigger/Cross soundtrack). The characters are so well done and the story is really something incredible.
If you can take mediocre gameplay in exchange for a well told story, you might like it...