And it is no wonder: WordPress has a huge developer and vendor community supporting it, there are numerous themes that allow one to use various website layouts and to switch easily between them without changing site content, and if you need additional functionality there are all kinds of plugins available.
But does this mean you should use it? If you are a web developer and want to stay competitive, then you should at least familiarize yourself with it. It is a great tool to quickly put together a relatively simple website for a customer the he or she can largely maintain on their own. If you are closely familiar with WP you can also develop quite sophisticated sites that again have the advantage of being easily maintainable by the customer.
If your are not a web developer, need a simple website, have time, and are technically inclined, then WP may be for you. It all depends on how simple of a site you need, how much time you have, and how comfortable you are with computers. Be careful: you may be tempted to start building a website, be successful at first, then run into problems and buy a few plugins just to realize that you are hopelessly stuck and need to fork out more money for more plugins or hire a consultant. In hindsight you may realize you would have been better off hiring someone in the first place.
Using WP, or another Content Management System (CMS), e.g. Droopal or Joomla, is like going to a Home Depot and picking up a kit to do some home improvement job. Depending on your background, available time, and job complexity this may or may not be a good idea. No analogy is perfect, though. However, I'm sure you got the idea.