I love Reykjavik, and can't wait for my next visit. It's a great city: small and eminently walkable, friendly and fun, traits paralleled by this little guidebook. I wavered between a four and five star review simply because of currency issues: the book was written in the middle of the Icelandic banking boom, and how the mighty have fallen since then. I really like the Wallpaper guides in general, though, and this one specifically. I decided on five stars in that the biggest changes newcomers would be likely to notice is lower prices in many areas since the book was published, making Iceland an even more appealing travel option. The recommendations in the book are still generally quite valid.
Like the other books in the series, this is a very small guidebook, which means it's easy to carry with you. It is fine for actually carrying around Reykjavik, unlike some of the gigantic guides, but you will definitely need another more in-depth guide for planning and reference. The photographs are splendid, the attractions they point out are in many cases similar to my own list of favorites, and the tabs make it very user-friendly; my favorite section is "Architour: A Guide to Reykjavik's Iconic Buildings."
This is a wonderfully little guidebook, and while far from comprehensive, I love it.