Anyone who has played it knows its Square's best story and close to the best RPG it has ever made.
If Xenogears had a final fantasy type budget, the 2nd cd would have been completely fleshed out and it would be considered the greatest rpg of all time. It's even rumored that FF8 stole money from Xenogears budget.
Even as it stands now, Xenogears, despite being pretty linear, still lasts around 75 hours of gametime and has more story to tell than a Metal Gear Solid game. Try and squeeze that amount of gameplay from current RPGs.