I am constantly amazed at how flexible WordPress is. Little over a year ago, I had only heard of WordPress, but had no real idea what it was. Then my husband started his blog, and I discovered it was like LiveJournal (which I had used for nearly 5 years), only better. Whereas LiveJournal was hosted, and locked you into a limited number of options, with WordPress you could host your own blog, and customize it however you saw fit. With a little CSS and PHP knowledge, you could change the whole look of your blog.
Even if WordPress was only used for blogs, it would still be worthwhile. After all, it’s free, highly customizable, easy to use, and can be hosted at your own domain. But with the large community of WordPress users providing plug-ins, you can use WordPress for more than just a blog. For example, at least 2 of the webcomics I read, Applegeeks and PvP, use WordPress to publish their comics. Using the YAPB plug-in, you can easily convert WordPress into a photoblog, allowing both photo posts and regular text posts. However you want to use WordPress, someone before you has probably already thought of it, and built a plug-in to do what you want. That freedom is what I like about WordPress; no matter what you want to do, you can probably manage it with WordPress.