We did -- here's my opinion for what it's worth. We had to wait with the Carnival people in the debarking/port area and rode the same bus they did. The person from the Turtle Farm seemed to want to keep it mum that we were Internet customers, so I didn't advertise how we'd gotten our tickets. We went for half what it cost the people who bought excursions; the process went smoothly and I would recommend going that route if you choose to visit the farm. Buy online, print your receipt (you will need to let them know what day you'll be in port), bring the receipt with you to the desk, they'll look you up and give you a wristband.
I would have been upset had we paid full price. I didn't feel we got to spend enough time at the facility itself; we didn't get to look at or go into the freshwater pool because my daughter wanted to spend so much time in the snorkel lagoon. She likes to snorkel but is terrified that if she steps a toe in the ocean a shark will swim up and bite it off. The snorkel lagoon was fun and non-threatening for her, but it was FULL of floating algae, not clean at all. There were a couple of turtles in there and a lot of fish, and you could look through an observation window where there were a few sharks and other things. I would have liked to go into the freshwater pool for a while just for some extra soaking time after all the algae in the other pool. It was pretty gross...but obviously we lived through it!
The gift shop really didn't have much of a selection.
The food was good, a BIT pricey but not as bad as I'd thought. I had the conch fritters as I have never tried conch before. My daughter ordered a bowl of turtle soup (her rationale was it's already dead so you might as well eat it). She said it was very good and it must've been; it was a very large bowl and she ate the whole thing.
There's a small aviary with very personable and genuine staff. The place in general looked like it needed some work. We had a downpour in the middle of lunch that didn't last long, some guy with a piano outside the restaurant starts playing "I can see clearly now the rain is gone" so of course we had to sing along...for some reason it struck me as hilarious...
Hope that helps