Salary vs. hourly rate?

Boss put me on salary without letting me know. They had talked to me about it months ago but was told I don't have enough people under me to make me salary so I stayed hourly. Now I am on salary and had no chance to negotiate a higher rate. I personally don't like salary since I would be exempt, so no OT for me. What are the benefits of being on salary? Right now I don't see any. I have a meeting with a sup. in a few days to discuss why it was changed without proper notice (can they do that?) Does anyone have any advice? Which one is better?