The theory of flaps is to increase the wing surface area thus increasing lift which will lower your stall speed. The downside is that they also substantially increase the aircraft's drag, which then needs an increase in power to overcome the drag. Contrary to popular opinion, flaps are not speed brakes. If the flaps are applied at too low an airspeed, the aircraft will pitch down. If they are applied at an airspeed above stall speed, the aircraft will pitch up. It just takes practice to figure out what is enough airspeed and what isn't. I have a Telemaster 40 with flaps that is setup for funflys. With the flaps down and in a slight breeze, I can hover the plane and land it like a helicopter.