The premise for 'Bonfire of the Vanities' is pretty simple, and one you'll be familiar with by now. The gameplay is also simple: it's pretty much just a string of assassinations. There are a few new additions, such as spring poles and if you buy the more expensive version three new Templar Hideouts.
Personally I didn't understand the spring-pole-jump-long-way-thing. Or at least how to use it: they were quite picky on positioning, and when you're running to try and avoid archers it can be a little difficult to get it right.
But they aren't essential to gameplay, which really feels like a way to stretch your assassination skills out of hibernation.
Overall, it's pleasantly short, and a nice way to fill in the final gap of the story.