We had a NYC Pass and originally planned to go on a different cruise but ended up by chance doing the New York Landmarks Cruise which lasted around 90 minutes. It was a good length of time - not too long but long enough.
Our tour guide was knowledgeable, although he made a joke to repeat his name over and over again I still forget, it may have been David? He was full of information and facts.
The snackbar downstairs was pretty pricey but it's up to you whether you buy from it or not, my wife wanted a hot chocolate and gave me a sad face so I bought one regardless of price!
We saw the Statue of Liberty among many other things, thoroughly recommend this cruise!