The Studs Lonigan Trilogy is James Farrell's masterwork and a classic of American "realism." Modern Library included the trilogy as one of the Top 100 Fiction Books of the 20th Century. It also shows up on the BOMC's list of 60 novels in it's Well-Stocked Bookcase.
I understand readers who complain about the book seeming dated. The slang the characters use, their clothes, even some of their concerns, are anachronisms now. But it strikes me as a spot-on description of the rough world of second generation, Irish Catholic toughs in Chicago in the 1920s. Definitely not the glittery 1920s of Fitzgerald or Dorothy Parker!
The final book of the trilogy, Judgment Day, is the longest of the three and my favorite. It has a lot more going on than just what is in Studs Lonigan’s head. This final volume really gives a compelling view of the Great Depression, focusing as it does on the middle class characters and what they lose because of the depression. Because these people have jobs, own their own businesses, invest in real estate, speculate on the stock market, they seem more familiar and relevant to me than dirt farmers (Grapes of Wrath), labor agitators (USA Trilogy), or other soup line characters from books and movies about the Great Depression.
Except for compulsive list readers such as myself, I would recommend skipping the first two volumes and only reading Judgment Day. It stands alone and, I think, is the best of the three.