Can someone here speak to the quality of this series?<p>They look like they're in a genre of book that I've struggled to see the case for in tech—the "for dummies" book. Culturally, our communities tend to produce lots of useful tutorials and documentation that's available publicly for free, so I've never been sure how beginner books like this find a market.<p>So I'm wondering if anyone who knows these books can recommend them over the free alternatives: would anything in this bundle be worth getting for a relatively experienced engineer? Is there anything worth recommending to a friend who's just getting started?