A phrasebook isn't going to teach you the language. I mean, what if you can actually use it to ask directions for your hotel? THEN WHAT? You won't be able to understand the answer anyway!!! At that point, you're better off just learning "Mi scusi, parla inglese?" (excuse me, do you speak English?). The best thing would be to take a group course before your trip.
Still, phrasebooks are useful to decipher menu items and for emergency situations. For instance, when you need to find a pharmacy because you've been walking too much and now your feet are full of blisters! How do you say "bandaid"? There you go! I'm OK with this book, but I think Lonely Planet's is easier to look through when you need to find something FAST.
Italian: Lonely Planet Phrasebook