It's great, but the same company offers a trolley tour that covers almost as much ground, has the same basic history and information from the guides, and allows you to get off and on at different spots - so you can see the island and stop to shop and eat at a couple of different places ... very cool. You can't do that on the conch train - you are stuck as the earlier guy says for 90 minutes.
I highly recommend it if you like history. Im not too much into history but I loved it. You learn about what old key west was like and if you like pirate stories this is for you because Key West was full of pirates! It is well worth the money and whenever I ever hear someone going to the keys I always tell them to check this out if not anything ...