keyboard not working on iPhone 4S after ios7 update

I have tried resetting my phone, the icloud shut off/on etc, everything short of a voodoo chant on my phone and nothing...no luck. lag time on the keyboard is at least 1 minute, i cannot see what i am typing and to auto-correct--- well forget it, takes too darn long and i can't see what i am correcting anyway

Hi Everyone!

I've updated my iphone 4 to the latest IOS7 update and when i come to text or type in general; If I press and "S" it will simply go to "A" . . .I have to let it come to for a little while until it works? I took it back to the shop and the guy said it was simply the software is too much for the Phone. I believe him, however is there anyway of fixing this? As I cant really afford an iPhone 5 :/

HELP!!!!