If nothing else, the Xenosaga series has been defined by how tumultuous its design decisions have been. The original introduced a likable cast into a futuristic, psychological romp that was marred by its mediocre combat. Its sequel lavished in changes, some necessary (combat) and some strange (a decidedly apathetic voice cast). The final entry truly rounds the experience, bringing a beautiful close to a contemplative, adult trilogy (which is more than I can say for upwards to 80% of JRPGs out there). If you have a passing interest in this series, start with the first one.