I love this book! I'd have to go with the majority and say the Marquis is excellent; a really un-likeable anti-hero, who I somehow can't help liking.
When the series came out I was 15, and spent a lot of time hanging around on the underground (back when it was cheaper) and it really caught my imagination. Croup in particular is excellent, and my other half still uses his inflection for 'naughty!' when he tells our kids off.
The book is better than the series, but I don't find that either gets in the way of the other, and for the supporting characters actually help flesh out the pictures in my head.
Love it! Love it a lot!