If the only valid point he has is that passive investments are a good thing, it's not a great personal finance book. You could learn a similar amount by looking up "investment" in a good dictionary.
The 'point' of the book is that this contradicts general beliefs of society. For example, that hard work is what gets one rich. Going from poor to rich does require hard work, but which work you choose to do matters far more than how hard you work at it.
If you read HN then you already understand the premise of the book. But for society writ large "Rich Dad, Poor Dad" was a wakeup call to reexamine core values and life choices.
