Is any of the Xenosaga stuff worth tapping into?
Soundtrack wise, or game wise?
Soundtrack wise, definitely "Yes!" The first game features Mitsuda with the London Philharmonic Orchestra at his disposal. It is really good. The second two games are also done by a good composer, it's not the same but really just as good, just different and less "cinematic."
As gaming experiences, I'm a bit more ambivalent. I can compare it to what a lot of people think about BSG, that is: it starts out really good, goes downhill and gets downright frustrating for awhile, and then climbs its way back up in a way that isn't what you'd initially have hoped for but still pretty damn gratifying. I'll give a game-by-game recap:
Episode 1: A solid RPG experience for people who really, really like good stories and don't mind a lot of CGI. Great soundtrack, decent graphics, a bit bland in terms of gameplay but the story makes up for it. Definitely a thought provoking and one of a kind game, even if it's missing some key RPG elements like towns and meaningful shops and the like. Takes about 40 hours to complete with sidequests. Things feel incomplete all-around, but it's still satisfying as you know there's more to come. Before Mass Effect, this game WAS the best Space Opera game! 4/5.
Episode 2: The masterminds behind the first game stepped down, leaving the series to a team of n00bs. These n00bs basically rushed out a product of what can be safely called "filler". Cutscenes are short and meaningless, dungeons are recycled, and little happens that advances the plot until the second disc. 3/4ths in, and things finally start to get good. It helps that the graphics are nice and the soundtrack is good. But the game's a downer. Unfortunately, it ends as soon (after about 25 hours) as things start picking up 2/5.
Episode 3: After the sell-out that was the 2nd game failed to do well either commercially or critically, the developers knew they had to do something good to win back the series. And boy did they ever! Episode 3 is probably the most complete-feeling of all three games. Since episode two basically failed to advance the plot in any meaningful way, there's a lot of recap in episode 3 in the beginning which covers stuff that happened between the first two games. But after that, it's smooth sailing. Episode 3 has great gameplay and a great story, and it's one of the best looking games on the PS2 to boot. The plot is a little weird, but the developers did their best to real things in from the atrocity that was episode 2 and is shows. Should give you a solid 50 hours of gameplay. 5/5.
So there ya go. I'd say go for it. Episode 2 is so fucking bad (in fact, it's level of hideousness has discouraged lots of people from even wanting to replay the series) but it's short and then soon you get Episode 3. Plus, how much would picking the entire series up these days cost, anyway? They practically give these games away in game stops now, right?