There's an interesting article in New Scientist in defence of the IUCN Redlist
THE IUCN's Red List of Threatened Species is widely recognised as one of the best tools we have for guiding nature conservation. It is widely used to identify species in need of conservation measures and sites of crucial importance for biodiversity, and also to track progress on reducing biodiversity loss and to guide resource allocation. It is not perfect and no stranger to criticism, most recently in the pages of this magazine, where it was described as "unscientific and frequently wrong" (New Scientist, 14 March, p8). This is wide of the mark.
Read the rest of the article here.
http://www.newscientist.com/article/mg20227026.600-in-defence-of-the-red-list.html