To be frank - I's now going to sound nasty, but seeing as I am a Dumas fan, I don't care

- Dumas is great on the good story front, that's it. He does not compare, to take a compatriot and one who dates from the same time, to Hugo. Hugo's prose is better technically, his message is better, there is a message as such. Dumas is simple on the prose front, less reearched onthe philosophy and literature front. Apart from the obvious ones like Fontaine and Molière and here and tehre some Shakespeare, he does not go for a lot of stuff behind his story.
Dumas produced stories, no more, no less. Though they are good stories, there is nothing much to find behind it that is not really obvious. Though Hugo, in his former days, as I have discovered by reading
Le Notre Dame de Paris, actually turned it up quite a lot in
Les Misérables, he still had more behind his earlier work than Dumas ever had.
That said though, his stories are great, and I find unbeatable. He started as a playwright and then went onto novels. That is why his dialogues are so great. But it's all on the surface, there is nothing behind it. There is not a whole world that appears when you start thinking about one word or so, like with Hugo, and his prose is sometimes rather sloppy because he used to write periodicals and did not revise a lot. The length of his sentences was so famous, even in his days, that people argued that he could not have written it and got exhasperated with his long sentences, which led to demonstrations on his part. Still, the simplicity of his stories makes his stories great and the passion that is embedded in it. He takes history and plays with it in an admirable way, sometimes fiddles with it a little, but still, the general idea remains and mostly quite well too. But in terms of philosophy etc, he is not a great no..