Stuart Kauffman once made some critical comments about memes. He wrote:
the concept of meme, and its descent with modification, is taken as a (or perhaps the) central conceptual contribution to the evolution of human culture. But the conceptual framework is so limited as to be nearly trivial. Like NeoDarwinism, it suffers from the inability to account for the source of new forms, new memes. Moreover, mere descent with modification is a vastly oversimplified image and understanding of how in cultural and technological evolution, new concepts, artifacts, legal systems, modes of governance, and modes of coevolving organizations at different level have come into existence in the past three million years, of how culture continues to transform today."Descent with modification" is an incomplete characterization of evolution - since most evolution also includes merging. Merging is very important in both genetic and cultural evolution. So: criticising the phrase "descent with modification" on these is reasonable - but it doesn't seem to have much to do with memes.
As for the alleged "inability to account for the source of new forms" - that's a vague and weak critique of modern evolutionary theory.
Update 2014-10-08: More critical comments from S.K. here: A Holistic, Non-algorithmic View of Cultural Evolution.