os4 wasnt terrible on my 3g, it just made the user experience much less pleasant. ie email took approx 10 secs to attach a picture and allow you to enter sender name - plus some apps could take similar time to load etc. so generally just too slow
so really hoping 4.1 can sort that a bit as dont really want to have to shell out for 4g just so it runs at a decent speed
maybe they will throw in background pics too
cheers
dan
