Japanese artist community pixiv puts out a "yearbook" each year entitled "pixiv nenkan". Starting in 2009, there are 3 books thus far, with the 4th book (for the year 2012) right on the horizon.
This book is an English translation of "pixiv nenkan 2010 official book" that is done quite beautifully by Udon Entertainment. It can be assumed that volume 2 will be a translation of the pixiv nenkan from 2011. I am unsure why they decided to skip the true first volume (which was 2009), but since I have the Japanese version, you won't hear any complaints from me.
From Japanese versus English perspective, I'm quite delighted to say that I actually prefer Udon's version to the original. Why? Because they did such a darn good job with the presentation and printing. The images are high quality and glossy, printed on thick matte white paper. The cover is gorgeous; unlike the Japanese original, they chose to print the artist's user icons in color. The glossy squares against the matte cover are just plain beautiful. You can tell they gave this book special treatment. It even comes shrink-wrapped from the factory to ensure it arrives in mint condition. This was a big plus for me, because books I order from Amazon don't always arrive in the best condition. (I've made quite a few exchanges due to scuffs and creases, mind you.)
As for the contents, the book contains a medley of images from pixiv's most prestigious members. If names like Sayori, Marukata, JohnHathway, Cuteg and more are familiar to you, you will see all of them in this book.
If you own the Japanese version of pixiv nenkan 2010, should you buy this book? If you love pixiv and you have the money to spare, yes. It's gorgeous and will support Udon bringing more great books from Japan to the United States. While the contents are mainly images, there are some articles in the back that have been translated into English that may be of interest to you. And of course there is the fact that I actually like Udon's printing more than the original. Once again, Udon has done a positively stellar job translating a fantastic book into English and giving it the loving printing treatment it deserves.