The first volume is only about 140 pages and follows a teenage Studs graduating from Catholic school and spending his summer going increasingly juvie as a reaction against his well-meaning parenting and a masked rage against falling in love with a girl.
Young Lonigan kinda works as a scrappy tale of Chicago in the 20s, with nice slang like "everything's jake." It feels like it must have established this "genre" of juvie kids out on the Chicago sidewalks. (I would be convinced Harmony Korine took his inspiration for KIDS from Farrell if I thought for a second that Korine was really into reading the Modern Library's 100 Greatest Novels and not vomiting into the Modern Library's 100 Greatest Novels.)
But the first book alone doesn't feel substantial enough to warrant your attention. I suspect that the shit gets good in the 2nd or 3rd installments, and if you buy a modern version of this book, all three are included in one volume. I will read on and let you know.
One additional note: There is a brutal chapter towards the end of the Irish no-goods bullying the hood's Jewish kids. Farrell clearly felt bad about this, though and suddenly invents a Jewish protagonist for the next chapter who calls the Irish idiots and waxes poetically about the genius of Jews.