Disadvantages:
There are some disadvantages of this method that are following,
a. First-order derivatives are required; it is not suitable for a designer to provide first-order derivatives.
b. There is not local control support.
c. The order of the curve is constant in spite of the number of data points.
d. Physically, the values of parameters a0, a1, a2 and a3 do not contain any intentive meaning. If you know these values, you can't imagine the shape of the curve.