It feels like you have to press the brakes all the way in to make the car stop, they 'bite' at a much lower point than they used to and it sometimes feels like the car won't stop.
The brake warning light has appeared on the dashboard and doesn't go out when the other lights do after starting the car up.
Looking at the level of fluid in the reservoir it appears to be below the level that it should/used to be.
When pressing the brake pedal the brakes don't apply in a smooth way, they seem to come on all of a sudden and are more bumpy than they used to be.