Excellent! Notes from the Underground became an inspiration, the whole genre was built on it. First of two parts (about third of the book) is a bit slower and harder to read, just so you know.
The Tunnel is very powerful book! I'm sure everyone who reads it would thoroughly enjoy (even though it's very disturbing :D).
I've read Crime and Punishment so I have a slight idea on his way of writing. I'm actually intrigued by his use of flawed main characters in his novels. Annoying, at some point, but effective.
As for Ernesto Sabato, it's my first time learning about this author. Thanks for introducing him to us. 😁
Sabato is one of the most well known Argentine writers together with Jorge Luis Borges. They actually met once and their conversation was recorded and turned into a book. :)
Unfortunately, he's still not recognized enough in the western world, but if you can get your hands on this book, don't hesitate.