My father was a carpenter, he built grain elevators for the Saskatchewan Wheat Pool for many years. One of the things he used to tell me is to always use the right tool for the job. This was usually just before I was going to do something stupid. Building websites is not much different, you need to use the right tool for the job.
I know that a lot of people out there love WordPress. They use WordPress for every website they make. They find it easy to use and customize and have a system for making their websites. The only problem is if you are using WordPress as a content management system you are using the wrong tool for the job. WordPress is a great platform for blogging, that is why I switched over from Blogger. But WordPress is not a great system for managing a website that is not a blog. The greatest features that I like about WordPress as a blog are the commenting and discussion and it is focused on the continual addition of new posts. WordPress also does a much better job of using RSS and allows syndication of the content very easily.
Joomla, is a great system for creating websites of all sizes, but one thing Joomla is not very good at is blogging. Joomla lacks a few features out of the box that make a blog unique, mainly the commenting and discussion ability of WordPress. I also find the RSS features of Joomla to be lacking. Sure it offers RSS but it is often restricted to home page content. You can add extensions to Joomla to make it behave more like blogging software, but it is just not as good for some reason. Joomla on the other hand is great a building websites of all sizes and giving webmasters the ability to add in many features including a built in advertising manager that many websites need. Joomla can also be extended to include ecommerce, directories, and many other features. Sure WordPress has plugins but Joomla extensions can often add greater functionality to a website than any WordPress plugin.
I know I will probably get flak from both the die hard WordPress and Joomla users, but if you are planning on creating a new website make sure you choose the right tool for the job. If you want a website that is more traditional but is still easy to edit and add new content to use Joomla. If you want to blog use WordPress.