I upgraded my iPhone to the latest version of the software on Friday, since when:
- it freezes and crashes constantly
- apps open and then close again immediate
- the battery life has deteriorated, for example I charged it fully overnight, and used it lightly today, lightly as I couldn't get it to play any music on my train journey in, yet by 2 pm the battery had expired
- the touch-screen often refuses to take any input at all
I've tried various tricks: removing the lock, turning off wifi, countless hard resets. If you haven't yet upgraded, dear reader, hold off, for heaven's sake.