I got this cable mainly so I can view the very large video files the 4s generates with its 8MP camera. My old PC just isn't up to playing these HD video files on Quicktime, and it's nice to be able to view them before I have to copy them to my PC and convert them to something it can deal with.
I'm on iOS 5.1. The cable works well but only with certain applications. It doesn't just represent the iPhone screen on the TV, like someone suggested the 'proper' Apple cable will do (never seen this, just read a review from someone saying that's what the Apple cable will do).
Here's what I've found so far:
Camera Roll: Videos play with sound; photos can be viewed from SlideShow only Videos: These play fine (as you'd expect!). Quality on a big screen depends on the quality/compression of the video (also as you'd expect!) Music/iPod: Music plays with a blank screen on the TV YouTube: Video with sound - same caveat on quality of the picture
BBC iPlayer: sound but no video ITV Player: sound but no video Other Apps: It varies. E.g Star Walk shows the night sky view but not some of the menus, other apps show nothing.
At £17 it's not cheap for a cable, but a lot cheaper than the Apple-brand equivalent.