Excellent reference, even for more seasoned astronomers (so I'm told). Concise, clear maps, as expected from Wil Tirion who also created the charts for Star Atlas 2000.
The basic layout is perfect, with seasonal maps of the celestial sphere, followed by sections and maps for each individual constellation and descriptions of their points of interest (Messier objects, etc.)
Lastly, it fits in your top pocket and is dirt cheap. What more could you want?