First, a GP is not an expert on ssris. Even most psychiatrists haven't a clue. Second, all ssris have withdrawal problems, and although it's true Celexa has been easier on the whole than, say, Paxil, or Effexor, if you go on withdrawal websites you'll still see plenty of severe withdrawal problems. He's put you on Prozac because it's a long-lasting ssri, whereas all the others are very short lived in the body; usually they'll use liquid Prozac so they can wean slowly.