About 2012 Responsive Webdesign was widely disseminated and it was one of the Top Webdesign trends in 2013. Last year Responsive Webdesign got commonly used and by now there should be no doubt that it is state of the art.
The usage of Responsive Webdesign realy simplified the development of mobile friendly websites. If you choose a new Theme for your WordPress site there should be absolutely no discuss to only pick a 100% responsive design.
But don’t just trust the theme developer that your site will look great on different devices. You should verify yourself. One of the biggest benefits of Responsive Design is that you can test it in your browser by just resizing the window. But that’s tedious and you never know how to resize your browser window to get a good idea of how your website looks on common device sizes. Plus you have to activate the new theme to see it in action.
This is how a potential new Theme can be tested for responsiveness very easy:
Install and activate the Theme Test Drive Plugin. This Plugin allows you to test any Theme by showing your website using a chosen Theme when you are logged in while other visitors still see your webiste using the currently active Theme.
There are several Websites allowing you to test the responsive design of your site. As long as the test site does not download your website via their server but by using your browser you can use one of them to test your desired theme. Just log in to your WordPress Dashboard, select the Theme for testing and open the responsive design test website in another browser tab to test your site using this theme. The way the testing sites display your Website in different device sizes not always 100% correspond to how it looks in real life. The best results I found on isresponsive.com. It shows some common device sizes and also the media queries for them (for developers…). And it most closely corresponds to real life display in my opinion.