Yes! Dune Messiah and Children of Dune are good sequels, Children is definitely the better of the two, neither is as great as the original but they're still worth reading.
God Emperor of Dune is very different and it was difficult for me to get into it at the start but it was really worth it, it's such a great book, probably my favourite Dune novel.
Heretics of Dune and Chapterhouse: Dune are great too, the focus shifts to the Bene Gesserit which made me very happy.
Avoid the sequels, prequels and interquels written by Brian Herbert and Kevin J Anderson like the plague, they are awful.