Georgs,
I have not personally cruised the North Coast of Cuba, but have close friends who have. The Trip to Marina Hemingway is straight forward and well documented. The North Coast of Cuba is subject to the Northers which come down the Gulf of Mexico in the winter, and can make the Norther Coast rough during those times.
Get Nigel Calder's book on Cuba cruising. It is excellent.
My friends had some minor problems getting clearance out of ports in a timely manor in the early morning, and they were not alowed to clear out the evening before and anchor out. All have had positive experience in Cuba.
The South Coast of Cuba is a cruiser's paradise--but not much in the way of supplies available, and a bit more difficult to get there.
I agree that hopefully Cuba will open as a destination and free trade will resume. This will be good for all!