>>walter+(OP)
The #1 problem I have typing on my iPhone is that I hit letter keys (mostly 'n') instead of the space bar and the phone just doesn't anticipate this as a possible typo and doesn't offer the right corrections. (I have AutoCorrect off.) It doesn't seem able to learn that this is a common typo, either.
>>thinkl+jJ
Hah! I have exactly the opposite problem, I hit the space bar, instead of N, and the iPhone doesn't understand this a possible typo, so all the suggestions and auto-corrects are wrong.