We use this book in my class, and I really dislike it.
The grammatical explanations are weak, and presented in an ineffectual way. They aren't organized well: the grammatical explanations almost get lost on the page.
The verb presentation was virtually a recipe for failure for my class. There was absolutely no discussion of why verb conjugation works the way it does, ie no discussion of 1st, 2nd, 3rd person, no discussion of singular vs plural (I took Spanish and German and have very strong English skills, so I understood this, but the rest of my class did not). The 2nd and 3rd conjugations (-ere and -ire) were dumped all at once along with a huge verb list including the -isc form of -ire verbs. I thought the -ere work should have been separated from -ire verb work, so students could gain some mastery of one first, and the -ire verbs (normal and -isc form) should have been broken apart into 2 lessons groups. No way should there have been a huge verb list with an introduction. Also, reflexive verbs were introduced as vocabulary with NO explanation of how to use them until well after the fact (why bother teaching them as vocab if not going to give the skills to handle them?) and the explanation was inadequate (it simply introduced piacere conversational usage without explaning that piacere is reflexive). If you have some prior knowledge like I did, you are ok with these things, but if not... good luck because you will need it.
I also did not like the dialogues. They included vocabulary that was not explained in the margin notes and also was not available within the book's translation glossary. Another annoying thing... they used compound prepositions (nella, sulla) early but with no clarifying info. So, its was unnecessarily difficult to understand the dialogues.
The English-Italian, Italian-English glossary at the back of the book was virtually useless. At a minimum, words used in the text should have been available in the back of the book.
The exercises in both the textbook and workbook were weak and ineffectual. They did not build strength in sentence writing skill or appropriately emphasize the grammatical concepts under study. Example: 6 conjugation forms, but practice only with Io and tu responses. Or, even duller, repeating the same sentence with only a single idiom exchange... a waste of ink and paper and time. I found it more useful to write out my own sentences using the grammatical elements we covered, because the book exercises did not adequately reinforce anything.
The online material was a pain in the neck to get set up. If you make a mistake in the set up process, like I did, you need to create a new email account to start over. The online exercises were every bit as weak as the book exercises. They were particularly deficient in building listening skills. There should have been aflot more listening content at an easier comprehension level in the beginning units. I found the speakers hard to follow because they spoke too quickly. Which, in chapter three, would have been ok, but to start, that was not a recipe for success.
I suppose you could make the case that this book is teaching conversational Italian, but I do not think it succeeds there, either. It is hard to make small talk conversation when foundation skills are so weakly wrought that it is hard to construct sentences on the fly.
I am sure there are much better books out there. The online content for Prego! looked great, I wish that book had been chosen for our class.