It seems Adi Shankaracharya: Hinduism’s Greatest Thinker is now $0.99 on Kindle, so I got a copy. From what little I know the subhead is warranted, so understanding Adi Shankara goes a long way to understanding elite Hinduism.
On the other hand, I have a dim view of most religious philosophy personally. But, it is important that people take such thinking seriously, as understanding it is a part of understanding humanity. For example, I can acknowledge that Thomas Aquinas was a brilliant thinker, while at the same time thinking his mind was wasted.