Any reviewer saying that this book was only common sense and that every adult should already know these things is simply not the target audience. This book has plenty of information for people whose parents didn't teach them important life skills. Is it all-encompassing? Of course not, however, it offers basic instructions for a lot of tasks that a parent could have neglected to teach a child. It also includes photos for a lot of this, which is nice.
However...
This is a book that is aimed at 16-25 yr old males, and I can understand that while also thinking a lot of the humor was unsavory. I don't need to hear about how the theoretical dollar bill in my pocket has "the remnants of a coked out hooker who has had one too many abortions" on it. I don't need to be warned "This one is for the ladies (just kidding, but not really)" at the beginning of the 'How to Parallel Park' section of the book. Yes, those are actual quotes.
I really wanted a life skills book that could teach me about properly filing taxes, but that is not this book. The only suggestion about taxes was "Hire a qualified tax accountant" and for the rest of the section on taxes he continues on to say that the reader probably lacks the ability to accomplish basic tasks on our own, so we should skip the trouble and hire a tax accountant. Not like the point of reading this book was to learn those basic skills or anything.
Overall it has a few useful tips, especially in regards to things like car and home maintenance, but every time it gets into the actual advice it is interrupted by juvenile humor obviously meant to engage the "new grad" teen boy audience. Which, again, isn't necessarily an objectively bad thing but felt obnoxious to me almost immediately and distracted me from the actual information.
Not a terrible book, and I learned some things and can see myself readily coming back to this in the future and reading a section when I don't know what to do. But I'm sure that there are better sources of information out there, perhaps compiled in a way that is a little less distracting and gag-gifty.