Ringworld and The Ringworld Engineers are some of the best hard SF books ever written. On the other hand, The Ringworld Throne was an enormous disappointment, and given that I expected to dislike this offering. I was pleasantly surprised. The characters are well defined as usual with Niven, and the story, while not too complex, runs along nicely.
The days of truly epic tales from Niven seem to be over. Nowadays, he writes little idea pieces like this one, or collaborates with other authors. If you enjoyed the first two Ringworld novels, you will like this one. However, I think it would be impossible to read without having first read the other ones, and probably some of the other Known Space stories.