It's a poorly planned, overpriced trip
1. Pickup may happen as early as 10.30/11, even for a 1 PM trip - so your effectively waste the day
2. It's not a small group - our group had 25 people oj one boat
3. There's no real activity- they take you to the island, and you stay there for 4 hours. Everything on the island (including seating that is 500 baht) is paid and extra
4. They docked back at 6.30, even though sunset was at 6.37 - granted it was a cloudy day, but there were better alternatives available.
Overall- you can avoid this tour. Coral isalnds by themselves are pretty - you can just to Chalong pier and charter a boat for much cheaper.