I didn’t like the characters AT ALL. The setting was kind of interesting (reminds me of Greg Bear’s previous novel, Hull Zero Three–which might have been inspired by Orphans), but the story was dragged out too much. Good climax but difficult getting to it. I’m afraid this has become a pattern for me, of disliking almost everything Heinlein wrote in his juvenile series.
These aren’t bad stories but just not worthy of the author’s later fame. I can speculate: Stranger was such an extraordinary success that readers assume Heinlein was producing that level of writing all along. Not so. His writing skill seemed to follow a bell curve, with Stranger at the peak in the middle.