To the OP if you have played the Xeonsaga series and never had the privilege of playing xenogears you are only cheating yourself my friend. Xenogears started the whole craze and for good reason it's awesome. the battle system also stuck with me and was very fun.
Certain characters will also stick with you, Citan Uzuki (the master), Fei or should i say ID (the man) and others i will not name because they will just ruin it for ya. However i will say this, the story is epic the battles are also epic and when you get to disc 2 and you get System ID(will not elaborate on that anymore) it gets even better.