This sounds like you might have read only the early novels which, yes, were mainly silly. Try Night Watch perhaps? There's a bit of background silliness - residual from all the world building that's gone on before - but to me it's one of his most thoughtful novels.

It's perfectly ok for them not to be your cuppa of course; my Mum and I loved them but my Dad never got into them despite trying quite a few times. Funny because generally our tastes intersected quite thoroughly.