What are the drawbacks of Lewis concept of bonding?

Lewis concept fails to explain:
(i) The cause of covalent bond formation.
(ii) The nature of attractive forces between the constituent atoms of a molecule.
(iii) The geometry of molecules containing covalent bonds.
(iv) The formation of molecules such as PCl₅, SF₆ and IF₇ in which the central atom has more than 8 electrons in its valence shell (violation of octet rule).
(v) The formation of molecules such as BF₃, AlCl₃ in which the central atom has less than 8 electrons in its valence shell.
(vi) The amount of enthalpy released during covalent bond formation.