I can honestly say I'm glad to hear concrete reasons why the movie is disliked. Most people I talk to just say how much better the other movies are, and don't say why the others are bad.
That said, to me the difference between the quality of Batman: Forever and Batman & Robin was that B&R took the stuff that was bad with BF (the "liberties") to an extreme that was impossible to ignore. I can live with completely revamping a character when it enhances rather than detracting the story. Hell, TAS more or less single-handedly made Mr. Freeze relevant by mostly revamping him.
That said, to me the difference between the quality of Batman: Forever and Batman & Robin was that B&R took the stuff that was bad with BF (the "liberties") to an extreme that was impossible to ignore. I can live with completely revamping a character when it enhances rather than detracting the story. Hell, TAS more or less single-handedly made Mr. Freeze relevant by mostly revamping him.