I feel like agreeing with the review that is currently at the top in comparing this show to 'The Lord of The Flies'. That's the sort of plot you should expect, and that's the sort of uneasiness you should feel when you get into watching this show.
I watched infinite Ryvius at a very leisurely pace. I think I finished it over the course of a year in fact. I watched some four episodes at the beginning of the year and then just forgot about it in the midst of other shows and life in general, until I had the time to pick it up again and proceed with it. When I did get to watching it like this I couldn't quite put it down, it's a really engaging show.
There is a healthy dollop of realistic science fiction that controls a lot of the show mechanics. Simple maneuvers of a humanoid machine require lot's of programming, no sounds in space, the classics. I like that sort of feel to the show, it makes situations that much more tense. And thankfully the young main cast isn't completely appalling or annoying, over the course of the time of watching this show you will fall in tune with most of the characters, and while you may forget their names you definitely won't forget the characters themselves.
A great dynamic cast, and a great science fiction tale to be told. It gave me a definate wistful feeling after finishing it, so it classifies as one of the greats. No, personally I don't consider it quite a masterpiece, but it's a very welcome watch for sci-fi, and definitely one of the greatest science fiction anime out there.
For the casual observer who isn't sure you'd watch this show: I can only suggest 'watch it until things first get bad'. However, the pacing is slow so there is no helping that.