Walsh has some interesting arguments, and she's certainly right that the Democratic Party has had little interest in representing the poor (of any color).
Unfortunately, I got bogged down in her poor white=white Irish Catholic outlook. I understand that's her family history. But it's also a pretty East Coast point of view. As a West Coaster I can say we don't have a large Irish Catholic population (which isn't to say we don't have a lot of poor working class white people or that we don't have our own set of prejudices). But it's hard to relate to her stories of ethnic insularity in certain occupations (again, not to say we don't have that here). It's just a completely different experience and for a book titled as broadly as hers is, I think she really needed to include perspectives from other white blue collar workers as well.
In addition, I take issue with some of her complaints about Identity politics. More than once she dismisses people who argue about what should be in history books as focusing on the wrong thing, but is then astonished when Progressive friends don't know the history of Irish Catholic Americans and labor disputes. How does she think those stories get included? And isn't it important to know a people's history so we all appreciate how difficult it was to make some of the gains that have been made? I don't deny that identity politics have plenty of problems of their own, but sometimes it's the best way to get something done. Does anyone really think gay marriage would be legalized in any state if gay groups hadn't been working toward it for years (sometimes with the help of their straight allies)?
I think my problem is that I was looking for more of an academic work and less of a personal history.