Wordpress is a scalable application that runs on PHP. The benefit of using a CMS like this is the admin panel and the plugins. If you are trying to build the next facebook or youtube, I would suggest regular PHP Development, but on the other hand if you are a small business or owner of a company this is a great way to have a lot of control over your website and have some (not all) customization options. One thing that truly great about Wordpress is the plugins. there is a plugin for almost every web service online now.