I liked Wordpress, it was easy to install and to add some prebuilt themes, there were a few mambots and extensions I liked as well. It is very easy to use for a one author many readers type site. But setting up groups of users with their own pages is very hard because it is not designed for it. Also, I was frustrated by the lack of integration of extensions with each other.
I would recomend this for a Blog we even set it up for Nu Skin to use on its intranet for new items but it is not very collabarative in nature other than allowing comments on blog entries. In otherwords it is not a CMS but great for a flyer
Here is how I set up Wordpress.