A good friend went a few years ago when there was a temporary lull in the enforcement. Basically exploiting a theoretical loophole in the regs that a cruiser was not spending money
in Cuba which is the actual ban. Travel is not banned specifically, you just cannot contribute to the Cuban economy.
Have not heard of any US citizens going recently but a couple of years back I heard that several who tried it were penalized. I would wait a year or so as it seems like the situation is changing.