I have been usig this book for some time and I think that it deserves five stars for what it is, mainly a catalogue of Portuguese verb tenses, with their endings and forms. But it stops there. The information you get is clear and reliable, but you need something else if you want to understand how Portuguese verbs actually work, how they behave in a sentence, how they compare with English verbs. I have now found an excellent book for all that, Portuguese Verbs Explained by Manuela Cook. It goes well beyond this one.