Crystal field theory (CFT) considers ligands as point charges and focuses on the electrostatic interaction between metal and ligand.
CFT is successful in explaining:
II. Formation and structures of complexes
III. Colour (due to d-d transition)
IV. Magnetic properties (due to electron pairing/unpairing in d orbitals)
It does not explain I (ligands as point charges is an assumption, not an outcome)
It also fails to explain V (covalent character), which is covered by Molecular Orbital Theory