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Limitations of Bohr's Model........

The Bohr model gives an incorrect value $\scriptstyle \mathbf{L} = \hbar$ for the ground state orbital angular momentum. The angular momentum in the true ground state is known to be zero. Although mental pictures fail somewhat at these levels of scale, an electron in the lowest modern "orbital" with no orbital momentum, may be thought of as not to rotate "around" the nucleus at all, but merely to go tightly around it in an ellipse with zero area. This is only reproduced in a more sophisticated semiclassical treatment like Sommerfeld's.

In modern quantum mechanics, the electron in hydrogen is a spherical cloud of probability which grows more dense near the nucleus. The rate of decay in hydrogen is equal to the Bohr radius, but since Bohr worked with circular orbits, not zero area ellipses, the fact that these two numbers exactly agree is a coincidence.

The Bohr model also has difficulty with, or else fails to explain:

Much of the spectra of larger atoms. At best, it can make predictions about the K-alpha and some L-alpha X-ray emission spectra for larger atoms, if two additional ad hoc assumptions are made. Emission spectra for atoms with a single outer-shell electron (atoms in the lithium group) can also be approximately predicted. Also, if the empiric electron-nuclear screening factors for many atoms are known, many other spectral lines can be deduced from the information, in similar atoms of differing elements, via the Ritz-Rydberg combination principles. All these techniques essentially make use of Bohr's Newtonian energy-potential picture of the atom.
The relative intensities of spectral lines; although in some simple cases, Bohr's formula or modifications of it, was able to provide reasonable estimates (for example, calculations by Kramers for the Stark Effect ).
The existence of fine structure and hyperfine structure in spectral lines, which are known to be due to a variety of relativistic and subtle effects, as well as complications from electron spin.
The Zeeman Effect - changes in spectral lines due to external magnetic fields ; these are also due to more complicated quantum principles interacting with electron spin and orbital magnetic fields.

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