I understand now that the cast of Xenoglossia aren't original to this anime, but debuted two years earlier in the original iDOLM@STER arcade game. If these are faithful adaptations of these characters, I can't say, but what I can tell you is that the characters presented here vary between good and great. I can pick out weaker, supporting characters, but I couldn't target any single member as poorly written. The development of the main, pre-existing characters is certainly one of Xenoglossia's strengths.
What I can't praise quite so much is Xenoglossia's music. It wasn't outstanding but it isn't bad at all either. There's one or two particularly nice tracks but overall it's simply 'good'.
There are two distinct halves to this anime, and the second is more typical of a mecha anime. Whereas the first half is very character driven and devotes most of its time to their development, the plot comes to the fore mainly in the second half. It's an admittedly strange plot but I still found it very enjoyable.
Overall, I think Xenoglossia is underrated. It's truly much better than it appears to be given credit for. I've read that is has since gained some popularity, and I would be happy if it continued to do so from now on.
