My wife and I just spent a week in Krakow and found this guide very useful. We've used the "Best of"s before in Dublin and Prague and, combined with Rick Steves' guides, these have helped us plan what to visit, determine where to eat, and where/what to shop.
This guide was easy to use and very portable. I like that the maps are clear and not overloaded with information. I could easily cross-reference a place described in each section with the map. The descriptions of places to visit and restaurants helped us decide where to go.
The limitation (if you consider this a limit) is that this guide is not as opinionated as Steves. The guide doesn't rate places like Steves does, so there might be a more hit or miss. But it does list more places than Steves does, which has helped us out. Case in point--we found out about the Silesian House, a former Gestapo headquarters that is now a small museum in Krakow. Steves never mentions this museum, but we found it in the Best of guide and thought it was worth the short hike. And sometimes, we've disagreed with Steves opinions, so these guides give us more places to potentially explore and not be restricted to just what Rick Steves likes.
So, in short, a good informative guide with handy, accessible maps. And we'd highly recommend Krakow. We spent a week there, over New Year's, and found plenty of places to explore.