I liked it as well. I've already been using Ansible for a while but found it be a good guide for a beginner, though I would suggest installing via pip over apt/brew/whatever.
Probably because he suspects that it will be more up to date than the PPA; however Michael DeHaan comments that Ansible themselves maintain the PPA so it will be as up to date as the PyPI version.
The other reason might be to support multiple versions of Ansible and its dependencies simultaneously, via virtualenvs.
We maintain the ansible PPA, so it's always as up to date as the pip one.
If you've got any feedback on the PPA packaging, we'd definitely like to hear it!