The Xeno games are 90% story and 10% gameplay for the most part. Those who play rpg's for the gameplay will probably want to pass on the xeno games because the gameplay is average at best.
However if story is what you mainly like to focus on in an rpg than you should definitely check both xenogears and xenosaga out. Both have stories much deeper than pretty much any other rpg out there (though the xenogears story is a little better than the xenosaga story in my opinion).
If both the gameplay and story are important to you in an rpg you should check the games out as well. You may like it or you may not but it is worth a look.