This is a well known book in the FIRE community, and a favourite of some financial advisors I’ve come across.
It’s a very US-centric book, but it does relate to the UK too. Essentially it says put everything you can into cheap Vanguard index funds (he recommends just 2 funds to US readers, which track the SP500 US stock market). It covers the joys of compounding, dollar-cost-averaging, and simple mechanical investing.
As a hand’s off approach it’s certainly attractive. However it does assume that the market will keep doing what it’s been doing for years. Personally this seems to eggs-in-one-basket for my liking, hence also being invested in property bonds and commodities.
The book is definitely worth a read though.