I think the random tables are quite bad. They encourage behavior actively discouraged by the 5E DMG (ie allowing the party to randomly encounter an Incredibly Difficult Challenge). Content is somewhat repetitive, looks like padding. The DMG is vastly more useful for anything you'd want to generate that these tables would be used for.
Puzzles aren't very inspired; mostly just a lot of number/letter things. Maps are clear-drawn, but not-too-involved. Adventures may help some fledgling DMs.
Overall, very simplistic toolkit that may be useful to beginners who just want more examples of what a dungeon might look like. But, unless they're taking adventures directly from this guide, they would make better use of their time listening to virtually any D&D podcast.
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