Rough Guides are structured completely different from most phrase books: The first several dozen pages give you numbers, days of the week, time, etc., and a 20 minute course in grammar. Oh no, you might be saying, but it is presented very simply. For instance it presents a handful of common verbs and their conjugations. So on one page you can see how to say "I have," "he has, " etc. and "I like," "he/ she likes," etc.
The rest of the book is split between, in this case, an English-Portugese dictionary, a Portugese-English dictionary, and a 20 page menu reader. What makes the English-Portugese dictionary pages unique, though, is that most every other page (at least) has dialogue boxes relating to the most useful word(s) on that particular page. For instance, when you thumb through the book for the word "live," you get the word itself, but also the phrases "I live in..." and "Where do you live?" It'll take you 10 minutes to find such a phrase in Berlitz or Lonely Planet in their "getting to know others' section. But because Rough Guide is structured as a dictionary, with hundreds of really useful phrases highlighted in boxes within, you can access something you want to say rather swiftly...and actually deliver it just a minute or so after looking for it. Add the grammar section, where you learn useful verbs and how to conjugate their past tenses, and the number section, and you can learn easily to chat with someone about where you are from, where you are going, where you have traveled thus far, what you like/liked, and so on. Likewise, knowing have to say "have" make sit easily to ask whether a hotel has rooms, whether the room has a shower (after thumbing through the book for the word for shower), etc. And when the answer comes back that the hotel doesn't have, or say "we have," you can actually catch what they are saying.
If still not persuaded, next time you're in a bookstore compare a Berlitz, a Lonely Planet, and a Rough Guide language phrase book side by side. Lonely Planet Portugese, for example, is basically several pages of basic grammar followed by many sections of phases you won't likely ever use. For instance, the guide provides several pages each of lists of occupations, nationalities, items of stationary, colors, insects, flowers and so on. Also provided are pat phrases to employ at a hotel's front desk, at a doctor's, at the optometrist, and eating out, among other mini-sections. The book, in effect, is set up to be taken out to be used once a day, if that. It's an improvement on Berlitz phrase books, but not by much. (Berlitz simply divides their books into 10 or so color coded sections such as: "sightseeing," "relaxing," "shopping," travelling around," "money," "eating out," etc.)
So, if you just want a book for emergencies (say, breaking a leg, etc.) then Berlitz and/or Lonely Planet phrase books will serve you well...in your pocket until you are faced with such a situation, since they do have many more specific terms (like 50 different parts of the the body), but if you really want to be able to say some things in Portugese on a daily basis during your trip you'll be much better served by Rough Guide Portugese. Cheers