I've followed F1 racing for almost 14 years now. All rookie F1 drivers say the sheer power of the brakes is the biggest surprise when they first step into a F1 car for the first time from a lower class. They say they obviously expect the car to be much faster and have tremendous acceleration, but they say there is no way to prepare yourself for how fast these cars stop.
Grand Prix cars and the cutting edge technology that constitute them produce an unprecedented combination of outright speed and quickness for the drivers. Every F1 car on the grid is capable of going from 0 to 160 km/h (100 mph) and back to 0 in less than five seconds. During a demonstration at the Silverstone circuit in Britain, an F1 McLaren-Mercedes car driven by David Coulthard gave a pair of Mercedes-Benz street cars a head start of seventy seconds, and was able to beat the cars to the finish line from a standing start, a distance of only 3.2 miles (5.2 km).
The carbon brakes in combination with tyre technology and the car's aerodynamics produce truly remarkable braking forces. The deceleration force under braking is usually 4 g (39 m/s2), and can be as high as 5–6 g when braking from extreme speeds, for instance at the Gilles Villeneuve circuit or at Indianapolis. In 2007, Martin Brundle, a former Grand Prix driver, tested the Williams Toyota FW29 Formula 1 car, and stated that under heavy braking he felt like his lungs were hitting the inside of his ribcage, forcing him to exhale involuntarily.
Also F1 cars are among the safest racing cars on the planet. F1 hasn't had a racing related fatality since the black weekend in Imola in 1994 when we lost Senna (arguably the greatest F1 driver of all time) and the rookie driver Ratzenberger in the same weekend.
Here is an example of how safe F1 cars are. Robert Kubica walked away from this accident with a sprained ankle: Robert Kubica crash Canadian GP 2007