Cheesy dialogue has always been part of what makes Star Wars great. A matter of taste I suppose.
IMHO special effects are no problem. CGI allows us to see things on screen that we could only dream of before. Its really not that different to using a miniature or even a costume; its just another part of the illusion. It does make the actors job harder, but not to a film-ruining level.
As for shallow characters; depends on the character. Anakin is certainly not shallow. The characters in ANH are all a bit shallow, mainly becuase ANH was made as a stand alone movie, not part of the whole saga. But still they more than deep enough for what is essentially meant to be a fantasy adventure story.
@Robopig: the story is complete as-is, their are not going to be any more episodes.