I just typed "post", I saw "post" on the screen, then pressed space and it changed to "list"!!!
Is it making some kind of analysis of how close to the centre of each key got pressed, and deciding on balance I was probably aiming for the l and the i rather than the p and the o? And if it does, why would it do that when post is a valid word (I could understand such an analysis if the word isn't in the dictionary and it's trying to find the best alternative match)? The only other thing I can think of is that it is applying some kind of syntactical analysis and trying to guess what I meant to say. Don't!
I'm convinced this has got worse since the earlier iOS versions.