First impressions. I get what posterous can do from the get go (faq). I don't have a clue what tumblr can do for me. I scrolled  through a load of self flagellation on the about page, and it still didn't tell me. Both have stupid names.<p>After working at a myriad of places doing web work, people tend to skimp on the important little pieces that make a site usable. A lot of the time it's style over substance.<p>I'd have thought tumblr could improve by having the login on the homepage. And I'd prefer to also find a simple paragraph about what it can do.