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