Prolog was never designed for function approximation, like Neural Nets, so there is no comparison. Machine Learning with Prolog is perfectly possible and not at all clumsy. In fact these days we can even say it is done elegantly, by raising everything to the second order of logic where deduction and induction become one and the same.

Let me know if you need links and refs, but please try to keep your knowledge up-to-date before making big, splashy statements like "Prolog is very, very dead".