I've been into reading about the art of criticism in recent days, all of it starting with reading Gissing's New Grub Street quite a while back, so I thought I'd share this link that I found interesting. Some other articles and essays I found of interest:
Oscar Wilde's The Critic As Artist, ca 1891:
http://www.online-literature.com/wilde/1305/
A Short Essay on Critics, by Margaret Fuller ca. 1840:
http://www.berfrois.com/2013/05/short-essay-on-critics-marga.../
The Decline of Book Reviewing, by Elizabeth Hardwick ca. 1959:
http://harpers.org/archive/1959/10/the-decline-of-book-revie.../
An Essay on Criticism, by Alexander Pope ca. 1711
http://poetry.eserver.org/essay-on-criticism.html
As for my opinions on criticism? I can't claim to know so much about the subject to speak with any confidence in it, even after reading all of the above (Sometimes more than once), but I really like what Margaret Fuller said:
My own opinions on criticism, from my brief readings on the subject, can't be summed up better than that.