"Ringworld's Children"

I finished "Ringworld's Children". Like I mentioned the other day, the last third of the book was better than the preceding, but didn't average out into a good book. It's been a long time since I've read a science fiction book, but I still expected more to the book than interaction with the ring. There was also the idea of the "protectors" and their drive to protect their people. Protector is Niven's next phase in a human's life, after the breeder phase that we know about, and brought about by "tree of life", which is actually a root. The drive to protect provided motive for the character's actions, but it was lame. With such a monumental engineering construct as Ringworld, it would be nice if there was more of a plot and some character development instead of riding on the coat tails of the immense artifact.