This is one of the best comic character-based novels to date, and the best of the DC novels I have read. There is great characterization, especially as the point of view focuses on Wally West nearly exclusively. His insecurities and lack of confidence as a JLA member are dealt with very nicely.
Basically, as with other JLA novels, a new villain is created and dealt with, leaving nothing to interfere with the comic universe itself, but adding nicely to the feel of the universe. There is a new speedster in Keystone City, one who is faster than the Flash. This new speedster's actions cause some calamitous world disasters, as well as a number of gruesome murders. The JLA are largely insufficient to the task, with only Wally able to oppose this particular villain.
There is great exposition, good atmosphere, and a great comic-book feel. A number of other JLA members make appearances, though for the most part they are incidental window-dressing. What I like is that Wally actually is shown to be a round character, with his disposition altered over the course of the story. I found the ending a bit unsatisfying, somewhat abrupt and without the resolution to the climactic encounter. Still, this is a great book, and it works even for non-comic readers, as I am a fan of old but not terribly up to date as of the last decade and then some.