This text is a great start to learning Amoy Hokkien (a Chinese dialect very similar to Taiwanese as spoken in Taiwan). Unfortunately the text is somewhat dated, but then again I would think that you could learn effectively from this or the courses sister volume Spoken Taiwanese, and simply learn to correct your speech to the modern norm quite easily. After all, if you have all the grammar and vocabulary you need, and understand the language, you should be able to modify it based on how you hear others talking. The base grammar and vocabulary of any language doesn't change that quickly.
As far as my review of the lessons, please see my review of Spoken Taiwanese here on Amazon.