This one's usually quoted as being the best of the series (and I personally think it is) but I still think that the adulation for it is a wee bit out of proportion to the actual merits of the film. There is an element of hyperbole to statements concerning the quality of this film.
I like Empire the most but one can't ignore the fact that it was the previous film that invented *everything* about the look and feel of the Star Wars universe. Star Wars exists without Empire. Empire could not exist without Star Wars.