Rumors started years ago that Firefox would soon be available for iOS. Those rumors seemed to die down for a bit until it really wasn't talked much about anymore. Many people assumed that it wouldn't happen. Then, seemingly out of nowhere, Firefox is now available for iOS!
My browser of choice is Safari. I prefer Safari over Firefox or Chrome for a few reasons (speed and syncing between devices are two of the reasons). Having said that, I also really like Firefox... it's a very close second choice for me. I know many who prefer Firefox over Safari or Chrome, so the release of Firefox for iOS is a welcome addition to the App Store for many, many people.