  We argue that the conclusion, `we cannot consider the Dirac approach as
fundamental and undoubted', made in the paper by Shestakova (Class. Quantum
Grav. 28 055009, 2011), is based upon an incomplete and flawed analysis of the
simple model presented in section 3 of the article. We re-examine the analysis
of this model and find that it does not support the author's conclusion. For
the theory of gravity neither the equivalence of the effective action nor its
Hamiltonian formulation is given by the author, therefore, we only provide a
brief commentary.
