I've seen this mix of cartoonish style with dramatic storytelling in french comics before, and I've found the highly expressive art actually gives the drama even more of an emotional impact.
You should see the "Donjon" series. Purely cartoonish art and style, with funny animal characters, and a bit of a sense of humour. It's also a series with dark, dramatic action, which only seems to get bleaker with each new title. And I love the heck out of it.