It is one of the funniest book I ever read.

Thomas Mann has the most subtle humour.

True. It's bad that these books are usually read by only young people. I remember reading Steppenwolf for the first time since teens and only then I realized how funny it was all around. Dostoevsky's The Devils is hilarious too, being very dark at the same time.

The same goes for basically all higher culture. Popular culture is usually unfunny because humor is considered a commercial risk.

It's a question of mindset. I read it as I was in university (studying german literature) and thought that I should read some of the canonical works. Well, it was (at that time) no pleasure and boring. After finishing I read on the back cover that it was supposed to be humorous.

Today I'm able to enjoy it, but because of my mindset ("read something important!") it was not possible.

Now (as a teacher for german) I feel even some of the real serious stuff (dramatic works like Emilia Galotti, Nathan der Weise) have some funny elements, you can see it even as a soap opera (e.g. Nathan der Weise: In the end everybody is related).

edit: grammar

I chuckled in many scenes and more generally with the Hotel California vibes, but the book is also transcendental, mystical and dead serious at times. The mix of it all is what makes it arguably a masterpiece.

I did find "Felix Krull" funny but not really feeling it in his other works.