Often times the Amazon review boards are mistaken for discussion boards or fan forums. This in mind, what I'm about to say is going to upset that crowd. I will do my best to be fair.
First, let's address the show itself. The show is starting to suffer from some production value issues during these later episodes. Things are starting to seem rushed. Mouths don't move when people are talking (i.e. Robin and Amen running down the steps in episode 15). People seem to be standing and sitting for quite a long period of time without moving their head (a quick way to fill up some air time without great effort). Perhaps I am being slightly petty on this point, but I've seen way too many good anime (with strong production values to the very end) to let it slide.
This brings us to the story and character development. The story is far from great and the characters remain lifeless and dull. I think many who disagree are bridging the many gaps in the plot with their imaginations or basing reviews on future episodes. I have not seen any of the future episodes and I didn't pay money to imagine the story.
The writers have given us one major plot twist on the third DVD and it's already going nowhere on this DVD. I'm not an extreme action junkie, I can appreciate well built suspense, but it seems to me like we should have been in and out of the factory, discovered what Orzo is, and introduces new levels of conflict by this point. The world of Robin is just too interesting to devote whole episodes on nothing. And this leads us to Robin's ultimate downfall...
It seems the writers are gearing this show towards a younger audience (which is fine). However, I like my anime to be a little more complicated than what is being offered. I'm used to the plot twisting and turning like a pretzel. Robin has let me down here. The only twists come in the curve of a boomerang that never quite takes off and keeps revisiting the same old threads.
To conclude, if this was ten years ago with virtually no anime market around, I might suggest owning Robin just to own something. However, it isn't ten years ago and, in my very humble opinion, you have MANY better ways to spend your anime dollar (Rahxephon, Cowboy Bebop, Last Exile, etc).
For the fans I upset, I apologize. Take solace in that this will be the last review I write. My Robin collection ends here.