If you're here just for dolphin watching, I wouldn't recommend it. You're 50-75 feet away from seeing the dolphins and they're not going to leap out of the water following the boat unlike other rides like the Thundercat dolphin watch which I recommend that instead where the dolphins leap out of the water and they're 10-15 feet away. I would rate it a 2/5.
If you're here for the whale watching, it's a 4/5.
We originally booked for the dolphin watch because we ran out of time and the tour was booked for the whale watching. 2 hour dolphin tour, it took us 1hr and 20 mins from departure to see a few dolphins 50-75 feet away just popping up the surface to breathe air. Not jumping out of the water or leaping or anything. Boring. 1hr and 40 mins, I think the Capt felt bad for just a few dolphins and sailed far deeper into the ocean where we found a pod of dolphins. By 1hr and 50 mins, even though we were suppose to head back, we went slightly further out and for a bonus, we saw humpback whales more than 100-150 feet away. While you can see them with your naked eyes, having binoculars is a must. Either bring some or rent on the boat. Same with your video/camera/smartphone, bring a telescoping lens to get the best out of it.
When the boat spots dolphins or the whales, it does stop and it rocks. Rocks a lot and also rotates to give every passenger on each side of the boat a fair chance to see the animals but doesn't help with the sea sickness. 10% of the passengers got sea sick. If so, go to the main deck and the rear of the boat to minimize the rocking motion and drink any carbonated drink to ease the motion sickness. Best to bring some ginger chews to ease the motion sickness.