Here is a detailed, 27 page analysis of specific “problems and anomalies” contained in the Companies Act 2006, compiled by the Company Law Committee of the City of London Law Society and the Law Society Company Law Committee. (It also has, as an appendix, a letter discussing the issues raised by Farstad v Enviroco.)
Coming at the Act from a more conceptual angle, here is a post from April 2011 highlighting the view of Arad Reisberg, Reader in Corporate and Financial Law at University College London, that the Act is “complex in a way that makes even an airplane look simple”.
See also: Everything that’s wrong with the Companies Act 2006, Part II
Farstad v Enviroco: The meaning of “subsidiary” in the Companies Act 2006