‘Tumblr’?

I’ve noticed a lot of great stuff showing up on Tumblr but haven’t gone so far as to sign up for an account. Has anyone else used it? How did it compare to the other social media/self publishing things? I’m relatively satisfied with blogger/wordpress but feel like most things just end up under the same sets of eyes (no offense intended to fellow bloggers) and would like to branch out into a bigger pool of potential contacts.