In March, I cruised to Jamaica, CG, and Cozumel on the Carnival Magic. I didn't dive in Jamaica, but went with the 2 tank shore dive through Don Fosters in GC. Had a great time with lots to see, no stress and no worries getting back to the ship. DF's did a great job!
In Cozumel I did 2 dives through Sand Dollar, and again, they did a great job accommodating everyone with intermediate sites that everyone could handle.
In my experiences (2 times now) booking dives through cruise lines, I have had no problems, been happy, and had great times. But I didn't expect advanced dives from booking through a cruise.
I take dive specific vacations for those.
BTW, I hope that you guys had a great time and please fill us in on the details when you get a chance. Looking forward to hearing how it went!