Hi bsmrashid,
Yes that will give a quads stretch but it will also stretch plenty of other things as well. It is very non-specific, there is no control of the hip position, the L/S will hyperextend, etc.
Also, the full flexion of the knee will put excessive amounts of pressure onto the patellofemoral joints. Also, it is not a functional position (but this point is less important).
I would only recommend that stretch for those who have been conditioned to perform it correctly with supervision and with sufficient training. It would not be one i would give to a group situation - more likely to give to a ballerina or circus performer as a rehab exercise.
But that is only my opinion of course...