Without the novelty of the original, there's not a lot to recommend this (first of many) sequels. For all the self-doubt & confusion of Paul, Alia, and Duncan's ghost, the characters are largely one dimensional. Herbert somewhat falls under the weight of his purportedly eon shaking majestic characters who rarely say or do anything clever or wise (particularly the Reverend Mothers here and in 'Dune', who are supposed to have the insight of millennia, but are essentially ineffective, even pathetic).
While the plot does offer an interesting unifying twist, there's far too much irritating (cf. C.J. Cherryh, particularly Rusalka) vacillation about choices. We're meant to be carried along in the tide of mysticism, but it just becomes some vague hocus pocus to excuse any arbitrary action or excess of confused introspection.
Some Messianic parallels: the disciples were, granted, confused when Jesus saw things so differently; Paul sees his destiny in sacrifice to save others, and is brave enough to do it. But we don't have the attractive wisdom and love of the real deal. Nor do we see the teaching result in good fruit; rather it's never even really addressed why Paul has this genocidal Jihad beyond his control - he's either not bright or not humanitarian enough to end it.