Otto certainly gives you a good exposure to Matlab. The many examples and problems will greatly help you acquire the expertise, if you can knuckle down and tackle them.

The other utility of the book is in learning the various numerical methods, independent of the specific language of Matlab that they are implemented in. There is a possible advantage to doing so with Matlab, as contrasted to coding the methods in a general purpose language like C or Java. Since Matlab is already optimised [in some sense] for handling such methods. And especially with easily accessible and powerful graphing routines readily at hand. In other languages, a lot of your effort will inevitably be focused on writing this routines, as opposed to actually dealing with the numerical methods themselves.