Good points, but you forget... in this case the management(restaurant owner) is part of the listening crowd...in fact he's the one who initiated this discussion forum in the first place(AGORA).
So since the management is always listening in and wanting to know what is up to satisfaction as well as what isn't. Thus I see no problem with griping and/or promoting what the mananagement has done or not done...as long as, as many have said ...it isn't repeated over and over again without at least some constructive criticism on how to fix a particular problem.