I haven't been, but it's one of the stops on a cruise I intend to take. Are you going on a cruise, or a multi-day vacation?
I ask because forum searching here indicated to me that Samana is not the right area of the Dominican Republic to do a quick 2 tank boat dive excursion from; the good diving is farther afield than it practical while a ship is in port (or so was my understanding).
That was a real disappointment, because I've only got one good cruise port that's dive worthy. Well, there're worse problems in Life to contend with than that...
Richard.