WordPress started to ‘grow-up’ about two years ago. Today it is head and shoulders above all other blog environments in all areas.
With the thousands of plug-ins and themes available I do not think there is a site out there that could not be reproduced by the WordPress engine and a careful selection of plugins. Their clientele runs from Joe Blow the Blogger running an off-the-shelf default theme (installed and operational and live in 10 minutes for no cost) to the WordPress VIP stable which includes CNN, BBC, TIME – even Flickr. Note that these huge organizations did not use a standard CMS – they chose the WP engine.