It covers many aspects of NumPy and also introduces SciPy as well as Matplotlib. The author includes a lot of examples and exercises and also shows the effects of some not-so-easy-to-understand functions using matplotlib graphs.
The book is easy to read, so you should make fast progress in learning NumPy. Overall, it’s a good read for NumPy beginners. Advanced NumPy users, who just want to look up how specific things work, are better of with NumPy’s documentation, though.