Are the dialogues to be taken seriously?

[Pipkin]

I don't think I've ever read a book with such terrible dialogue. Having just started out, I will keep reading as the mystery side of it is indeed interesting.
But the characters all seem to be caricatures, full of stereotypes and exaggerations. I can't read the dialogues and character thoughts without cringing for the most part.
So, since everyone else seems to love this book, judging from the reviews, I am wondering: what am I not getting here?

Were cops intentionally made stupid (everyone other than Shroeder) or stereotypical? The lawyer and his assistant talk, behave and think like people from 200 years ago. I keep waiting for them to tell their servants to get the carriage ready for an excursion.
The Steels... I mean, come on...

Sorry, this is turning into a rant. But I do really want to know, what it is I'm not getting.