If you are looking for a really simple (at least on the surface ) content management system then Concrete5 (http://www.concrete5.org) ticks a lot of the boxes.
Created first in 2003 is its like many CMS php based and again open source so free to use. It boasts a lot of nice features and has a strong user community supporting it which is typical of open source applications. The goal of the system was for it to be easy, flexible and robust . Read more of the Concrete5 history on their site
One of the features that it advertises strongly is its in context editing which is attractive to the novice user or to the website ownew who is happy with their content and only really wants to make minor edits to the site. Personally I like this from a first impressions and I can see how it would be hugely attractive to people who are even uncomfortable with a lot of the editors that do come with a lot of the more established CMS. however if you are doing some hevy duty editing it can quickly tire and the desire to eitehr use a WYSIWYG editor or a better HTML editor does beckon.
Most of the CMS that I work with have this editor but it is an offline editor and the page isn’t in your face.
Ultimately this is still a php based CMS and has a lot of power and add-ons like many of the other CMS that are out there. One thing I do like about it is that unlike WordPress it has a rich set of video that shows you how to do the basic tasks which for users ultimately is edit, add image and make small everyday changes. It has a rich showcase of example sitea and themes to pick from. It would not be as comprehensive as WordPress and DRupal in its depth of add ons and community but I think that is not a negative for the type of user it would attract.
Saying that a lot of website design houses do use as their Go To CMS and it cvan be as powerfulas you wish once you have the right mix of development skills.
I installed Concrete5 here on a sub domain and this is my concrete5 playground for the next few weeks and I will be posting some articles as I learn and enjoy a new CMS.