Unfortunately, I can not tell too much about the diving in Cuba. When I've been there I had quite some trouble with my ears, so I could only dive twice in Maria la Gorda.
However, one thing to consider -and I never thought of before - is that Cuba is a socialistic country. Without going into a political discussion here this is worth mentioning because it says something about the general attitude. The word "service" has only very little meaning in Cuba. So if you are used to a system in which customer satisfaction is of importance to run a business, Cuba will teach you there is also another way to keep a business running - just do not allow any competition ;-)
Why do I mention this? For me personally diving is not only the underwater but also the overall experience. If one part does not live up to my expectations I have a hard time enjoying the other part. I can cope with next to zero service level if only I know beforehand and adjust my expectations accordingly.
The diving itself can be quite fun they have some nice corals and canyons there. As mentioned earlier I have been diving there only twice so I do not feel to be able to draw the full picture here. From what I heard from other divers, it seems that all the dive spots are quite similar and mostly very nice (I'd say 8 out of 10 points). The diving is relatively free, meaning that if the guide realizes that you know how to dive they let you go your way - or, and here I have to speak for the guides, they let you pass through the canyons first, knowing that the other divers will mess up the visibility by "grinding" the walls. That is probably because when I was there it felt like there were some people diving for the first time, which could very well be as they do not check your license.
However, at Maria la Gorda they offer three dives a day, the boat returns after every dive so you can choose for yourself. The first two dives are a bit deeper, the third dive will be shallow. No night diving, as the guide does not have a torch (?!?) .
My plan to dive at Cayo Largo and Isla Juventud did not work out simply because we did not go there. In Guardalavacca there also is only one dive center. I have been there but then could not dive due to my ears.
In retrospect I regret a bit that I could not dive more but I guess I was already fed and spoiled because I spend a few days diving Cenotes in Mexico before we went to Cuba.
