I went to Japan for the first time last year and brought with me the DK Eyewitness Guide to Tokyo and a Lonely Planet guide for the rest of Japan. I wish I had brought my DK Japan with me instead of Lonely Planet, because it turned out that DK was about a hundred times more helpful than Lonely Planet.
The DK Guide is well-organized, with sections at the back on the intricacies of public transportation, ordering meals, and etiquette. They wisely include a map of the Tokyo subway line on the inside cover, which is very handy.
The list of attractions is thorough and generally up to date. Every traveler will have a difference of opinion on what should be emphasized, of course. For instance, I would have highlighted the wonderful store Japan Sword over the somewhat disappointing Japanese Sword Museum, but, then again, I never would have known of Japan Sword's existence were it not for this book.
Because Tokyo is so large, it can be difficult to hit everything you want to see and do on a single trip, even if you have several days there. Happily, the DK guide is organized by geographic sections of the city (West, Central, and East), so you can group together attractions in close proximity to one another as you plan your day. It's far less scattershot in its organization than other guides. Every listing includes the attraction's lettered & numbered subway stop and directions for how to find what you're looking for when you emerge from the subway. (But whatever you do, don't come to Tokyo without a decent compass! Maps along the sidewalk don't necessarily have North pointing up.) There is also plenty of information about suggested day trips from Tokyo that are easily accessible if you purchased a Japan Rail Pass before you entered the country. (There's info on Japan Rail Passes in this guide, too.)
For more notable shrines and temples, DK includes highly detailed illustrations of the grounds with specific points of interest. Following their lead will reveal some hidden treasures that other tourists may miss.
There is also a handy section on common words and phrases, with correct pronunciation, that is very user-friendly.
The one major drawback of DK--and the only reason I took the Lonely Planet Guide to Japan instead-- is the weight. Due to its thoroughness and glossy pages, it is rather heavy, which is a problem if you're concerned about keeping the weight of a backpack or shoulder bag down. However, DK Tokyo doesn't weigh too much and is compact enough to fit in the side pocket of most cargo pants.
It was instantly obvious to me once I reached Japan how valuable DK Tokyo would be. So what if the cover photo is out of date, as one other reviewer mentioned? That's no reason to pass it up. It is still quite current and extraordinarily helpful. Reading it carefully before you depart will relieve a lot of pre-trip stress and answer a great many questions. It will also help you determine what you want to see and how to make the most of your time in one of the most endlessly fascinating cities on the planet. I recommend it completely.