Ringworld

I understand that Larry Niven's Ringworld is a sci-fi classic, but while it was a modestly entertaining read, I wasn't overwhelmed by it. The concept of the Ringworld and some of the other hard-sci-fi concepts were certainly intriguing. But the characterizations of the protagonists, human and otherwise, were a bit flat and strange; the ending of the book was abrupt and not gratifying, resolving few of the many ongoing story threads. Apparently the story continues in subsequent novels, which I didn't realize at first. I thought I had picked up a standalone novel. Although I liked it, I'm not sure I enjoyed the book sufficiently to read the rest of the works in the series.