While some third-party Web browsers (particularly iCab Mobile) are way more powerful than the stock Safari iDevices come with, I still prefer the latter. The reason for this is simple: Apple, at least in the pre-iOS 6 times (I haven't tested iOS 6 in this respect), has strictly forbidden to activate (via a simple call to _setDrawInWebThread()) flawless, stuttering-free scrolling in third-party browsers. Consequently, third-party browsers scroll around Web pages in a visually really annoying way.