The advantages are already posted. They are strong and even if more expensive than plastic boats to build commercially, they are relatively easy to build by an amateur.
The real disadvantage is weight that makes them slow boats. That is not a problem for bigger boats but it is a real problem to smaller sailboats.
Regarding smaller sailboats (- 45ft) I think aluminium is a better material. The French amateurs boat builders use a thick aluminium that dispenses internal framing and that makes it almost as easy to work with as working with steel and permits a lighter boat and faster boat.
Marine Auctions - Australia, Brisbane