Salmuel L Clemens as a book critic

It comes as no surprise to me that Mr. Clemens would have decided opinions on the writings of others. Anyone who has read beyond Huck Finn and Tom Sawyer would be aware that he was a man of far ranging interests and concerns. NYT has an article about the discovery of marginal notes in books from his personal library donated to the Redding Connecticut Library.
"In honor of the centennial of his death on April 21, the library granted The New York Times permission to examine this trove of books and record notes and markings Twain left behind in their margins."
Since the books were in circulation for much of their existence, and the library collection was culled of slower moving items at times (as all library collections are), there are not a large number of the Clemens/Twain volumes left.