The Q-Brain incorporates 4x 20A speed controllers in 1 device. All motor leads are pre-installed and are terminated with 3.5mm bullet connectors. Leads are 25 cm long which means that you can use this controller with frames up to 60 cm. It operates on 2-4 cells lipo and 5-12 cells Ni-XX (anyone still using these). Refresh rate is over 400Hz.
Weight of the speed controller is 112 grams and dimensions are ~70x62x11 mm. The Q-Brain is probably very similar to the Hobbywing Quattro ESC.
Advantage: Easy install
Disadvantage: If one of the esc's dies you can't use it with a quadcopter anymore (get a tricopter!)
More information on the Hobbyking site
Note: If you are using the Q-Brain with a KK2 board, then S3 (the white cable) has to be connected to M1 on the KK2 to power it.