VLC, the bestest, fastest, sweetest codec-filled and easiest to use is video player around, is now available (again) for free on iOS. If you're looking to play videos on your iPhone and iPad, VLC is probably going to be your best bet.
MacStories spent some time with the new VLC app and though it looks pretty much the same, it's supposed to be improved:
VLC has been completely rewritten to use modern audio and video output modules, multi-core decoding, and support for any file type supported by VLC on the desktop. In my tests, the app was able to quickly start playing any video file that I threw at it, such as .mp4 and .mkv files.
The app also lets you adjust playback speed, tweak brightness, contrast, saturation, etc. and supports subtitles. It's a welcome return to VLC which was kicked out of the App Store in the beginning of 2011 [App Store via 9to5Mac, MacStories]
Update: It seems for some reason it's been pulled from the UK App Store in the last 10 to 15 minutes. We can't quite work out why, so might be worth trying in an hour or so.