Firefox for iOS is now available in the App Store worldwide supporting both iPhone and iPad.
Due to restrictions imposed by Apple, Firefox for iOS will not feature Gecko, the core engine that normally powers Firefox, instead Apple's Safari and its WebKit engine will power the browser. This is, however, commonplace for other browsers on the iOS platform, such as Google's Chrome.
Mozilla is quite late to the iOS party and it will be interesting to see how users respond.
Source : http://www.neowin.net/news/firefox-for-ios-is-finally-here