I've been using Joomla and am pretty happy with it, though I don't think it is anywhere near as friendly as Wordpress from an SEO perspective. Given WPs new "widget" abilities has anyone considered moving from Joomla to Wordpress for their blog-like/lots-of-new-content type sites? Waptap
I been using Wordpress for blog all the while. I've never considered Joomla unless there is a need to build a large system consisting of many integrated modules where blog is a secondary feature.
For complex site, yes Joomla! will do it, and from the SEO perspective, Joomla! do it well with some hacks and components
Joomla is much more SEO friendly than wordpress out of the box. But its easy to change wordpress than joomla. IMO