I just watched Episode 1, the anime is just an anime adaptation of the game series it looks like, very good stuff. I guess this would be good for people who didn't play the first game and want to move on to the second one right away, although since Xenosaga has a good story I suggest it to anyone. The anime was very consistent with the events in the game, very cool to watch if you have played it.

The first episode was from (SPOILER)The beginning, when Shion tests KOS-MOS in the encephalon to the part where the Gnosis attack the Woglinde and KOS-MOS wakes up and tracks Shion. The episode ends as KOS-MOS wakes up.

I'm downloading Episode 2 and 3 now, can't wait.

edit:: It looks like the anime version will also be a lot more uncensored than the games might be able to be, for instance, there was some cursing in episode 1 which I think makes the dialogue more effective.