Junk, just pure junk.
If it wasnt for the special effects then this movie would be up there with some of the poorest I've ever seen. The thinnest of storylines is padded out with random and contrived passages of action and as for an insight into father and son relationships, I've seen more moving encounters in a Marx Brothers film.
Is this the result of when an actor become so big, that it really doesn't matter what he does, people will still pay money to see him? I can think of no other explanation.