Fat finger syndrome, in my experience the typing speed is really quick on iphone, though you can easily get errors....but....the predicitive text is really good at picking it up, and I find that I'm so slow typing on small keyboards that the extra speed of the touch screen makes up for time lost with spelling errors!
Though I have to say I think it's probably personal preference, may not suit everyone, but suits me just fine.
Again sounds like a trip to a shop to have a look. Then buy one from the US for my Vodafone account