Is The Intelligent Investor a great book for amateur investors? And does the algorithm, theory and experience in it still resonates with the present now?

I personally liked the book because I inculcate some principles of value investing to my style. However, I think certain metrics are outdated and even Warren Buffett has spoken about this since early 2000s that traditional metrics such as P/E and book value has no value to helping us make a decision.

To answer your qns, I personally feel it's not a good book to start with. There are much easier reads that encompass broader perspectives.

1. Profit from the panic - Adam Khoo

2. The most important things - Howard Marks

3. Understanding Market cycles - Howard Marks

4. Poor Charlie's Almanack - Charlie Munger

You may want to check "the Swedish investor" and "Financial wisdom" on youtube, they are YT channels that summarise and do commentaries on books. They highlight key takeways of a book in 10-15 minutes of illustrations that are easy to follow. You can check them out before choosing which book to read in full(:

Nothing about finance has really changed since a century ago. Things just move faster now due to bots. The book teaches many principles which are still very applicable today.