This is very useful for looking up the most commonly used Python functions. The biggest problem is remembering a) which module the thing you need is in and b) where that module is in the book. A good index of modules/functions would be a big help. Essential Python by Beasley has probably superceded this book for most Pythoneers.
A good idea and it seems to be well done. However, who is it for? A Python expert probably doesn't need this book. A Python non-expert will often be able to find something quicker in the free online documentation. Although it's a book of only 75 pages, searching through all of them for some vaguely-remembered function is tedious and time-consuming. If it had a good index, I'd give it four stars.