Plaster ceiling allows you to have different designs and is interesting if done right. Many people tend to overdo it and the effect is worse. The trick is keep it simple rather than complicated.

Pros:
1. Cleaner and aesthetically better looking as you can hide cables and wiring; fix downlights; install cassette airconditioner while hide the ducting; hide fan hooks, etc etc.
2. Enhanced look if done right

Cons
1. Additional cost
2. Lower the ceiling height.