The books alone are enough to grab you and make you forget that your lunch break is only an hour long. There are photo books on Bob-Lo Island, Detroit's historical theaters, the origins of the auto industry and tons of other topics. The artwork - which is mostly photography - includes great pictures of the old Hudson's store, Tiger Stadium and a bunch of other Detroit landmarks. The store is kind of like a mini-museum, except you're allowed to touch stuff.
Find Pure Detroit in the Guardian Building's "Retail Promenade". If nothing else, it's a great excuse to check out the Guardian Building itself.