Mayer offers great insights into economic thinking with mere common sense and asking the right question. The final chapters go into more theoretical spheres and look at regression analysis which can be a powerful. Mayer does a good job on making it very explicit how data can be manipulated and stats made to show other stories. And also why sometimes 'both are right' to some degree applies.
The book comes with a warning and it is painfully accurate. Being in the know about economical principles changes the way you look at the world and many things that seem good (on the political spectrum that would be the left - which Mayer considers himself to be on as well) fall apart. It makes you wonder why so often people just do not bother to ask the right questions. One of the most basic questions rarely asked is 'and then what?'. For most people the first consequence of any action is where they stop thinking. But you really have to go beyond and look at that incentives and issues arise out of the new situation. And so, many things that sound very promising suddenly sound like they come at extraordinary costs and at times even go completely opposite to their own intentions. And those intentions might be good, but the policy to attain them can fail and backfire.
Pointing these things out to people will sadly get you no brownie points. In fact, being able to view the world with more nuance and figuring out facts over feelings might turn you off to many ideas you held dear. There were many economic ideas I certainly liked and pushed for and might have joined a protest or two in favour of, but now that I understand the policies and their effects better - or rather, I understand what it actually is and not what I want it to be - I had to let go of many of those ideas, seeing how they often bring about contrary results. But people who do not understand economics as you might after reading this will not want to listen and remain in their bubble of sweet ignorance. And that can be difficult to reconcile with.