When I first read the Dune series in High School, Messiah seemed dreadfully boring - almost enough to quit reading it. After re-reading the series about 15 years later, I was very surprised by how much my opinion of Messiah improved - to the point that it's almost my favorite of the series. It really provides a stark (but satisfying) 3rd act and ending to Paul's story. I almost feel like it's Dune Part 2, rather than a separate novel.