I bought them. They aren’t bad. Mostly they are of use to introduce new areas and provide historical and cultural backgrounds and a sense of place. They tend to have little or no practical info about transportation and accommodation.
To be honest though, if you go to the various websites (especially the main tourism website, the sites for the various national scenic areas, and the forestry reserves) I have posted in the sticky threads you will find most of the info there and often a great deal more. The forestry reserve site, for example, provides pages and pages of info on each of the 14 or so reserves around Taiwan.
The magazines are cheap, however, and the pictures are good to inspire you to get out and explore.