Lonely Planet set the benchmark for travel guides, and their Taiwan guide really delivers.
It has a huge (and VERY informative) section on the cultural aspects of Taiwanese society, especially important information on subjects you would not normally think about such as its diplomatic relations with China, essential do's and dont's as well as basic etiquette.
There is a comprehensive list of Accomodation in three different price ranges throughout the country, as well as sights and sounds, attractions and 'must see/do' locations.
Full of helpfull maps and tips as well as many pages of full-colour pictures showing what there is to look forward too. One of the most helpfull things in this book however is that all place names and attractions are shown in English AND in Chinese characters. As anyone who has travelled outside of the English-speaking world will know, its very easy knowing that you need to get to a place called 'Sunny Gorge' but its a different matter altogether trying to recognise it. At least you can try to match the words up with this guide.
Don't arrive in Taiwan without this guide, it will save you time, money and stress!