Ranked in these QuestionsQuestion Ranking
Pro Easy install third-party themes from website
Vast collection is available here:
Pro Configurable themes
Not only you can edit downloaded themes, some of the themes are configurable from the get-go, so you can specify what you want before you click install.
tracks the browsing history of its users
Con Does not sync across different PC's
you will have to download all the styles you want to every PC you want to use it.