I had no idea this was meant as a sequel to Golden Voyage. (Spoilers)
I always thought that Sinbad movies were unrelated seeing as they were made years apart and seeing how Sinbad had already married a princess in The 7th Voyage of Sinbad. However, he doesn't seem to wind up with Margiana at the end of The Golden Voyage of Sinbad (he must be crazy) and that leaves room open for this to be a direct sequel.
According to the trivia, they considered having John Phillip Law return. I'm actually kinda glad that they didn't bring him back. He's a better Sinbad than Patrick Wayne, but I really prefer to think of the Sinbad films as unrelated stories rather than having two or all three being in the same continuity.
With all due respect, this film just isn't in the same league as its predecessors. 7th Voyage had the best monsters. Golden Voyage had the tightest story. This film just feels tired and empty by comparison; even a little bit cynical. ("I added four more eunuchs to the population.")
It's still worth watching, but it suffers from that third installment weakness which plagues a lot of trilogies.