When I signed up in the early days, it was awesome. They were the simple and concise, yet ridiculously powerful alternative to tumblr - email post@posterous.com, get a blog. I loved showing it to people because it was so amazingly simple.
I understand that wasn't quite enough to draw users in and they needed to evolve the product, but especially with this latest revision, my initial reaction was that I have no idea what Posterous is anymore. The messaging on the home page is terrible - "What's a space? A place for whatever!", and nowhere is the product itself shown.
As an existing user, my first reaction was to check my existing Posterous sites to make sure they were still blogs, and not Google+/Facebook-style Pages. And as a new user, I don't think I'd understand why I'd want Posterous in addition to Google+ or Facebook. (I understand that Posterous is better about privacy, but the competitors all claim that too, and Facebook never gave a shit about privacy - why would a new user believe Posterous?)
Again, I get they need to change their core product (or at least how it's positioned). I'm just really not sure a psuedo-social-network is the right way to go about it.
Even more than that, I miss the simplicity of "E-mail us anything. We'll post it for you."