Most WordPress themes are ready for the mobile web right out of the box. No need for additional customization, or investing thousands of dollars into a custom built website that’s designed to work with mobile browsers.
Using a responsive theme will ensure your website looks great, no matter the screen size it’s displayed on. This means that as new screen sizes are introduced and become the new norms your website will be equipped to handle them, without any more work on your part.
WordPress is over 10 years old. Which is like 100 in Internet years. The benefit of using a more mature platform is that most of the kinks have already been worked out. You’ll also notice that since it’s been out for so long a lot of the security issues have been patched.
Put simply, WordPress wouldn’t have thrived for as long as it has, if it wasn’t effective and useful.
Need we say more?