The VBT has some short comings:
(i) It does not provide insight into the origin of the characteristic colour of the complex ion
(ii) It does not distinguish between weak and strong ligands.
(iii) It does not give quantitative interpretation of the thermodynamic or kinetic stabilities of coordination compounds.
(iv) There is no quantitative interpretation of magnetic data (magnetic moment).
(v) It does not explain why some complexes are inner-orbital and other are outer-orbital complexes.
So to remove most of these short comings Crystal Field Theory (CFT) is introduced....