I went there in 2002, and thought it was pretty cool! It does not take a long time to get through - maybe an hour and a half at most. Some exhibits just really caught my interest - the one with the conjoined animals was so bizarre! I don't know if it's a must-see, but I enjoy these kind of places, so I was glad I went.
I'll give you a nice hint - if you go, whatever you do there, DON'T ROLL YOUR TONGUE!! : (you'll see!)
I also been to the one in St. Augustine, so I hope I'm not confusing the two here!
I was there a few months ago. It's kind of cool if you are into bizarre and weird things. Some of it is hokey, I'm sure that is why they say "believe it or not".
One of those touristy attractions, and it's something to do if you have time, but I wouldn't make it a "must see" priority IMO.
I like it and its fine to spend maybe an hour ( remember to pick up these tourist guides as they will often offer discount coupons - ok so $1 per person is not a lot but it helps) - gives you more money to spend at WDW
It is also close to Wonderworks and Pointe Orland complex.