Yeah, WP is not for serious projects. Something simple and a bit functional - that's what perfectly feets WP.
WordPress is the most widely used CMS and most of the WordPress users do not even know how to code. You can easily add a blog in your website with WordPress. But it depends on your application requirement that either you should use it or not. One of the biggest downside of WordPress is the security. Using the third party plugins in WordPress can cause sever security vulnerabilities in your application.