Though the iPhone keyboard was the best for my sausagy fingers, typing is still a real chore for me.
Then I stumbled across m'man Andy Naselli's list of applications he uses, one of which was Dragon Dictation. This is a free application from Nuance, that turns dictation into text.
It's very intuitive and accurate. Just open the app, tap a button, say what you want, tap again — and out it comes. Tap again, and you can copy the text to the clipboard, convert it to a text message, or email it. So far, I love it.
This review deals with the security of the app, and here is a detailed explanation of using punctuation.
If you want it, I suggest you get it now. It isn't likely to stay free forever.