I adore Prague and have read so many guide books on the city you wouldn't believe! This is by far my favourite... true it's wordy and lacking in photos, so if you're just visiting for a weekend and want to see the obvious sights, you may fare better with other guides.
I rate this guide above the others on the city purely because of the research and detail that has gone into its creation. Sure others tell you what to see when you arrive, but this one takes the extra step and holds your hand whilst you travel around the sights. I like that! Then again, maybe I just like tantalising trivia :)
The best way I can describe it is... other guides I've read on Prague tell you that the Trade Fair Palace (National Art Gallery) exists and how to get to it... this one tells you about the highlights of the collection, which floor they're on and a little bit of detail or history about the piece of art you're looking at. I should also point out at this point, that despite all this wordiness, it's also refreshingly straightforward and easy to read.