I travelled around Taiwan armed with both this book and the latest edition of
Lonely Planet.
Both were very good, but if I had to choose one, it would be the Rough Guide. I found it just as good for practical info, but it is much more detailed, covering activities like hiking, and in general exploring off the beaten track, in far greater detail.
It also has excellent, insightful and up to date background info on various interesting subjects, such as religious life and aboriginals.
Can't recommend it highly enough - and if you still need convincing, see the reviews on Amazon's US site, too!