I have not read very much of Hemingway's material, but I really enjoyed The Sun Also Rises. It was a bit slow at times but I found the overall plot and the portrayal of different characters intriguing. I particularly found it interesting how Hemingway represented Robert Cohn. There are several anti-Semitic statements throughout the story that lead the reader to question Hemingway's views on this matter. The treatment of Cohn by the other characters is terrible and I personally felt sorry for this guy who seemed to have struggled with this sort of resentment for his whole life.
I actually saw a similarity between Hemingway's Robert Cohn and Edith Wharton's Simon Rosedale from The House of Mirth. Rosedale is a Jewish character who is repeatedly described as having negative characteristics thought to be associated with the Jewish race. Like Cohn, Rosedale is an outcast in his social circle and society does not truly accept him as an equal to those who are in his same social class.
Although Edith Wharton wrote The House of Mirth several years earlier than the publishing of The Sun Also Rises, I think that the same motivation that lead to the creation of Rosedale inspired the character of Cohn. Jewish immigration to the United States boomed in the 19th century. In fact, 1/4 of the population in New York City became Jewish in the late 1800's. Because of the sudden increase in Jewish immigrants during this time, many people, authors included, began to convey a fear of the Jewish character and motivation. It was a belief by many that Jews were coming to overtake the American businesses at the expense of anyone who might get in their way. This along with other misguided stereotypes may have resulted in the anti-Semitic representation of Jewish characters seen in literature around this time.
If anyone is interested in more information on anti-Semitism at this time and in The House of Mirth you can check out my Wiki paper on the subject from a year ago. http://houseofmirthantisemitism.pbworks.com