I wouldn't really bother buying any text books that aren't on your reading lists, because you will only end up spending a load more on your core textbooks when you arrive!
General psychology reference books such as a psychology dictionary, or gregory's 'oxford companion to the mind' would be useful to give you some background knowledge of key people/movements in psychology, and will be useful for reference throughout your degree.
Edit: they probably recommended Pinker because some of his theories are extremely influential, regardless of how poorly written it might be, what he says is often important/controversial stuff! It is useful to try and read some of his original text to form your own opinions when you're learning about his theories, but i wouldn't worry about it before you even start your course, it is a bit dry out of context!