Beenhakker has a very good track record, winning 3 league titles with real madrid, 2 with ajax and 1 with feyenoord. Also he qualified saudi arabia for the world cup. However, we should not get too carried away.
He suddenly quit Ajax in 2003, coached America in Mexico in 2004 and got fired because they did not win anything although they had big name players like Blanco playing.
Don't misinterpret what I am saying. He is a very good coach and it is a very good move to hire him, but let us not be blinded.