Children of Dune is definitely more engaging that Dune Messiah, but I surely missed having Paul as the main character. Ghanima and Leto II take center stage, except that it's mostly Leto II, whereas Ghanima takes a back seat, being the "weaker" one. I don't think I ever got around to caring for Leto and in fact I found him strange and boring. The big secret of the Preacher was not really a secret at all and it would have been more surprising if he had turned out to be someone else.
I thought Leto's transformation was bizarre and it seemed the mechanism for him to do so was shoddily thrown and convenient. Hey if you just stick your hand in the sand...presto! I realize that it required a complex mind and understanding, but really now? However, the whole concept of it was fascinating. I have mixed feelings about this book. If you like Dune, it's a good read, but the focus on religion and politics can be overbearing at times.