They were full of breathless promises of what you could build and do, but were often full of typos, omissions, bad fonts and formatting, and often had covers (in this case) of "computer" graphics that no personal computer of the time could accomplish without a minicomputer rendering it for them. The electronics books were even worse, the "Encyclopedia of Electronic Circuits" often just looked like a child's project report in that things like manufacturer's block diagrams and unobtanium proprietary parts were often presented as useful things. I still have fond memories of entering and debugging programs from these books, and some of their electronics books still have useful information. But on the whole, they were bad, bad, bad, bad books. Bonus points if you remember all the weird unrelated woodcuts and clipart that these books used for illustrations.