A simple observer is proposed for a large class of multi-output nonlinear systems. The main characteristic of the proposed observer is its implementation and performance tailoring simplicity. Indeed, the gain of this observer does not require the resolution of any dynamical system and is analytically given. Moreover, the performance specification is made through the choice of a unique parameter. The performances of the proposed observer are demonstrated through a real experiment dealing with the estimation of the rotor flux, the motor speed and the load torque in an induction motor.