Whether to buy this book or not depends entirely upon what you want to achieve and how you want to achieve it. If you want to achieve an extremely high standard akin to that of taking a proper course at a university or equivalent, then this book is not your first port of call. If, however, you are planning a trip for holiday, business or something that requires a thorough knowledge of the basics and a comfortable feel with the language, then this is exactly what you want.
Icelandic is extremely hard to learn and possesses an ancient and hugely complex grammar which for the casual language learner is almost a joke. Words can often have over a dozen forms and these forms are integral to the sentence, which means a lot of memorising by repetition. This book introduces this large amount of grammar gradually and very clearly. It is well paced and it doesn't seem daunting which is useful when trying to handle inflections, and after a while you find that everything falls into place. The dialogues are good and as useful as language books ever are, and everything is done with a sense of fun which takes the pressure off a bit.
There is one major drawback to this book, and this is the CD. I understand that this is a very different language and it does require a bit more patience, but these dialogues are spoken so slowly that they are actually unhelpful. Soon after studying Icelandic and Iceland you will come to realise that, sadly, Icelanders speak very very fast and they don't slow down to help you out a lot of the time, and if they do this is still fast. These dialogues are so unrealistic in their pace of speaking that while you learn good pronunciation, you lack a realistic ability to keep up. I was saddened to see that this pace did not pick up much even in later chapters.
That said, if as I say you are a casual learner, this will not be a huge disadvantage, but if you intend to learn quicker I highly advise buying "Colloquial Icelandic" by Daisy L. Neijmann - an exceptionally good book that is a very different approach but much harder for real beginners. For beginners though, this will meet your needs and will introduce you to a really fascinating language with a sound basic knowledge enabling you to pursue it further should you wish to. Worth the money for sure.