They continue to be an excellent resource for certification preparation. Because books have been a mainstay of learning for more years then there are bugs in beta code, you'd think that the art of instructional book design would have been universally perfected by now. Unfortunately, that's far from true. The format, quality, and usability varies considerably from publisher to publisher, and even, less often, among books by the same publisher but different authors. This is partly because different formats appeal to different readers, but also because publishers are striving to create formats that work well for the specific task of certification preparation.
Technical accuracy can also be an issue.
Unfortunately, it does happen. To be fair, it s rarely due to simple carelessness. Certification preparation books usually cover intensely technical topics in intricate detail. Often the material is either cutting-edge or very close to it. Authors and publishers have to move quickly to compile, publish, and distribute this information to outlets where we can obtain it.