Ranked in these QuestionsQuestion Ranking
Pro Provides information about competitors
Alexa, in addition to on-site metrics, provides traffic, engagement and reputation data about other sites.
Con Unknown ranking accuracy
Alexa's ranking is based on users that have installed one of their browser extensions and sites that have installed a tracking script. It's unknown what kind of users are installing the extensions and how big is the sample size (Alexa claims it to be millions).