I've not had enough of an opportunity to play with Apple's auto-correct, but I've seen enough around the intarwebs and from friends to guess that it's fairly aggressive and isn't as easy to override as other platforms. Your comment kinda confirms that.
Actually, until I thought of this, I really wondered how people could get tripped up by it, as I've experienced several generations of Sony Ericsson's as well the Android one.
Wade.