Not to be short or disrespectful, but this is one of the most common subjects here on rv.net. Do a search on toad brakes and you'll get a whole bunch of info.
Personally I have one of the very few brake systems (see signature) that actually utilizes the toad's vacuum assisted "power brakes". Most others do not, and if you've ever had to use a car's brakes with the engine off, you'll understand the amount of force required to stop the car without power brakes.
Ron