This is like a cross between a Philly Cheese and a French Dip. It could be made better with the addition of a thin layer of horseradish spread on the matzo brie before adding the onions, meat and cheese. Also, sauteed mushrooms would be a great addition.
And of course, this is only kosher for Passover if you a) are willing to eat moistened matzo, which some people avoid, and b) you either don't keep kosher otherwise (I only observe Passover for the tradition, not for the religious aspect, really) or you forgo the cheese, since meat and dairy together is a no-no.