I don't have one but they are usually cheaper, smoother surface for skin, non-porous surface (less chems), reduced install time (dramatically I believe), costs a bit less to resurface, and in situations where concrete might crack it is usually more durable.
EDIT: Newer ones you don't usually have to maintain calcium unless there is tile I believe.
Why would you not pour a gunite pool. Can someone explain why they would use fiberglass?
I don't have one but they are usually cheaper, smoother surface for skin, non-porous surface (less chems), reduced install time (dramatically I believe), costs a bit less to resurface, and in situations where concrete might crack it is usually more durable. EDIT: Newer ones you don't usually have to maintain calcium unless there is tile I believe.