As for character, I also wasn’t sure if spending so much time with one character would hold my interest. Again, so far so good. For one thing, astronaut Mark Watney is worth spending time with as he grapples with his many life-threatening challenges and complains about, but is mesmerized by, the 70s TV shows he happens to have with him for entertainment. (They were left behind by his crewmates, who are on their way back to Earth.)
For another thing, we’re not stuck reading about just one character. No, it’s not that little green men suddenly appear to keep him company, and I seriously doubt there will be any in subsequent chapters. It’s not that kind of book. Instead, so far, there has been the very moving scene of the people back on Earth at NASA realizing that they’ve left a man behind. Watney is alive, but they appear to have no way of communicating with him, much less of saving him before he starves to death.
Can’t wait to see what happens next!