Obligatory "Firefox on iOS isn't really Firefox, as iOS App Store rules ban browser engines" reply. ALL iOS browsers are basically just skins on top of Safari's WebKit.
An off topic question, but I would appreciate feedback: I have tried the DuckDuckGo browser on my iPad, and it seems like it provides good privacy features even though it is layered on WebKit. Any opinions of DuckDuckGo vs. Firefox on iOS?