Before I used "Responsive", I worked with "zbench" in combination with "WPtouch". But this try was very slow, compared with "Responsive".
This theme is really responsive on various mobile systems. It works also for Android, the obsolete Symbian, the obsolete Bada, and - as far as I know - also for Apple devices.
Its setup is easy and self-describing. My favorite is the clear and clean view. And so I think, it is the best free theme I ever used since I work with WordPress.