Wordpress is probably the easiest CMS to work with as an end-user. Originally created specifically for blog-oriented web site, the CMS has now spread out worlwide and is certainly one of the most used CMS on the Web.
Wordpress is extremly inuitive. The administration of your site has never been that easy: click on your page, edit your content, save, done, it's online!
Con's includes the difficulty of adding very powerful third-party extensions but most of the time this is absolutely not an obstacle for small to medium web site.