The iconic Uncle Sam is living as a bum on the streets of modern America, while in his mind he is stumbling through history reliving some of America's darker moments. As he searches to remember who he is (the elusive American Dream), he is confronted again and again with his past failings. Uncle Sam is less a story than it is an extended political cartoon, and as such it suffers from the same problems as any political cartoon: taking a weighty subject and oversimplifying it. What might be excusable in a short few panels becomes a sledgehammer when strung out over the length of the story. The thing is, I actually agree with much of the message: America has a complex and sometimes sordid past; and we don't really live in the idealized world that we like to imagine. But here Steve Darnell's metaphor often overshadows his story, and at times it borders on the whiny side that lefties are often accused of (which doesn't make them wrong...just annoying).
Alex Ross' painted artwork is technically good. It has that Norman Rockwell feel to it, which some people love. For me, it always comes off stiff and cold (I much prefer his sketches).
The story is followed up with a short essay on the history of the Uncle Sam icon, which is easily the more interesting part of the book. Like the Pledge of Allegiance, Sam is one of those aspect of Americana that we assume is timeless and unchanging, but in fact has gone through an interesting evolution.