I'll start with the bad. The author of How To Be A Genius has left a fairly large amount of blatant typographical errors all over the whole book, and sometimes they really distracted me or confounded the text I was reading. In some parts of the book, key information that was supposed to be there (for example, the key used to break a code in a codebreaking brainteaser) was accidentally left out or was otherwise missing. It happens a few times, but it's not the end of the world. The only other problem I have is that every now and then a description of how to apply some kind of practical method for being more intelligent doesn't entirely explain what to do or is kind of lackluster. This is again not a huge deal (and for $10 this book has a really, really high density of useful information in it). I would give 5 full stars if not for these few sorts of things.
Looking past heavy typos and the occasional bits of missing information, a lot of How To Be A Genius contains useful information, and while it's probably not a be-all-end-all definitive guide to becoming a genius, it's certainly a great start. If you can take the information you find in this book and branch out into your research, you'll be well on your way to rewiring the ways you think into a more productive arrangement. The "missing information" problem I've encountered only applies to a few odds and ends, but the meaty informative sections of the book are all there and worth the read. Hopefully the typo problems can be revised for future buyers.