I've read three of his books, and although not all are "great", there's always some interesting thoughts about what he shares. I also like that he really gets people to develop a sense to actually think and work deeply, and move away from shallow and unsatisfactory busyness.
His newsletter and now his podcast are excellent ways for people to ask questions and get suggestions and help for free.
He has a bit of a big ego, but I wouldn't use that to call him "another BS self-help sales person".
Teaching productivity is not like teaching mathematics or philosophy. There is a limited range of things to learn and apply, and the core ideas are concise but difficult to put in practice. A good teacher in that space would essentially be able to impart their wisdom in maybe two hours, at which point the success of the teaching would lie in the student actually following what they were told. An ongoing productivity podcast or book series flies in the face of this. The mere act of commercializing productivity dooms the entire edifice. If the student is still on episode #23, the sales has succeeded but the teaching has failed.
[1]: https://www.youtube.com/playlist?list=PL8xK8kBHHUX43VVxO3b7s...
The productivity genre also never seems to provide empirical data to back up their recommendations. Like it would be great if these gurus actually conducted experiments into the best notes-taking systems. Evaluate them against each other with real results.
Oh, you say that every person’s best system is going to be different? Then maybe an innovation in this genre should be helping readers figure out which system should be best for the self, rather trying to prescribe one-size fits all systems and merchandising it with bullet journals and paid tools and the like.
Everybody else has turned hocking productivity advice into lucrative careers.
However without reflection that may include notes on notes, you are doomed to the suboptimal or even counter-productive.