This edition of Granta, themed around the city of Chicago, is very heavily slanted towards the reportage/memoir articles. If you are expecting the usual mix of these and new fiction, therefore you might be disappointed. Further, I didn't particularly enjoy the major pieces of fiction that are present; Nelson Algren's Irish-American boxer story was not particularly inspiring and the longest fictional piece, an extended extract from Peter Carey's Parrot and Olivier in America, (although this extract is entirely set in the UK so any link with US in general or specifically Chicago is tenuous at best) didn't inspire me to rush out and buy the book.
I've always loved Chicago for its vibrancy and architectural beauty but the non-fiction here paints a, probably accurate, depressing set of stories of immigrant life, violence, corruption and drugs. To what extent this is limited to Chicago, I couldn't say, but it's a sad picture of modern urban life. The articles are mostly well written and get under the skin of the city that the traveller doesn't see.
For me, the most effective pieces are the shorter memoir pieces that manage to show rather than tell about a particular aspect. Thus, Tony D'Souza's recollection of a car crash and Dinaw Mengestu's recollections of returning to Chicago on the illness of his father to run his message business really say more than the more about the city than anything. And Richard Powers relates a amusing story of civic planning ineptitude that would be even funnier if it wasn't true.
Nobel Prize for Literature winner Wole Soyinka writes about Barack Obama - although I found this a bit heavy going - and most aspects we associate with Chicago are given some coverage (manufacturing, the Lake, the architecture, the music, immigrants and the cold to name a few).
All in all, a bit of a mixed bag.