  We analyze the perturbative implications of the most general high derivative
approach to quantum gravity based on a diffeomorphism invariant local action.
In particular, we consider the super-renormalizable case with a large number of
metric derivatives in the action. The structure of ultraviolet divergences is
analyzed in some detail. We show that they are independent of the gauge fixing
condition and the choice of field reparametrization. The cosmological
counterterm is shown to vanish under certain parameter conditions. We elaborate
on the unitarity problem of high derivative approaches and the distribution of
masses of unphysical ghosts. We also discuss the properties of the low energy
regime and explore the possibility of having a multi-scale gravity with
different scaling regimes compatible with Einstein gravity at low energies.
Finally, we show that the ultraviolet scaling of matter theories is not
affected by the quantum corrections of high derivative gravity. As a
consequence, asymptotic freedom is stable under those quantum gravity
corrections.
