Instruct: Classify Amazon reviews into positive or negative sentiment
Query: There are better ones

If you are interesting in the kind of thoughtful, critical philosophical inquiry that is practiced in philosophy departments, where the focus is on giving reasons for one view or another, not on woolly rhetoric, the two best introductions are: Nigel Warburton, Philosophy: the Basics, and Bertrand Russell, The Problems of Philosophy. Don't bother with this one.