Yes, WPtouch uses its own themes for mobile devices and not the desktop theme. The main advantage over responsive themes is speed— since WPtouch only sends the files it needs to show for mobile visitors, page speeds are much faster than typical responsive themes, which have extra CSS and JavaScript to handle display for many different display sizes.
Additionally, we designed WPtouch to work alongside many other plugins for WordPress, while most responsive themes have zero support for 3rd party plugins and solutions.
It’s a matter of preference— some customers find that their themes don’t work or look that great on mobile devices, and go hunting and find us— a product that’s designed specifically for mobile.
Since we’ve been building themes designed for mobile for almost a decade, we’ve put a lot of hard work and dedication into providing great mobile experiences for mobile visitors.