VSEPR theory has certain advantages over Lewis dot structures. Some of them are described as below:
Lewis structures are effective in prediction about number of covalent bonds formed by an atom. However, Lewis structure does not give of electron density in molecule. Bond pair of electrons does not remain stationary as Lewis formula suggests.
Lewis formulas do not give the correct shape of molecules. For example, Lewis formula predicts bond angle of in water molecule linear shape as shown below:
However, VSEPR theory correctly predicts the angular shape of water molecule as shown below:
Lewis dot structure fails in molecules involving third or higher period elements. It simply cannot predict the stability of molecules such as etc. The sulfur atom has more than 8 electrons in molecule.