How can you pack an entire introductory course in linear algebra into under 200 pages AND make it enjoyable to read? Janich knows how. There is virtually zero fluff here. This is both good and bad, however. Janich teaches you what you need to know, and doesn't waste time explaining the same thing 10 different ways. The down side is that if you don't get a concept straight away, you'll feel lost.
There is a distinct lack of examples and exercises, and the exercises that are given have no solutions provided. This means that it is very hard to rectify any misunderstandings you may pick up.
This book makes for an excellent companion text, and serves admirably for review purposes. But if you need to learn how to apply the abstract concepts, you will want a second text that contains plenty of examples and exercises. As a lecturer once told me: Mathematics is not a spectator sport. You have to do it, not just read about it.