It greatly oversimplifies a complex process, ignoring modern developments in the field of evolutionary biology (including the entirety of population genetics), and makes many unfounded assumptions.

The Spandrels paper I referenced above explains in detail, and is a good starting point:

http://rspb.royalsocietypublishing.org/content/205/1161/581

Here's a more modern critique, which I posted here a few weeks ago:

http://bmcbiol.biomedcentral.com/articles/10.1186/s12915-016...