Yann Gourvennec makes an interesting point about user friendliness in his recent post (linked below)
[…] it may happen that a feature, which seemed user-friendly, and convenient in the beginning, becomes useless and irritating with time. For instance, we could describe the T9 (so-called ‘predictive text’) feature on mobile phones as very useful when we discover it for the first time. When you don’t have a keyboard on your mobile phone or your smartphone and you want to type a text (short message, note, calendar entrey, etc) this feature may seem really great and useful. You start typing the beginning of the words, and then the system will fetch into the dictionary and will complete the entry. However, with time, this feature appears quirky, and even generates unwanted effects. As a result, the feature which was meant to simplify usage becomes cumbersome, superfluous, and it even gets on your nerves to a point where you actually de-activate it (as long as you are able to work your way through the menus to re-instate manual entry). Eventually, users and mostly youngsters prefer to use abbreviations, and even this weird phonetic SMS lingo to communicate. This is a good example of a feature which seemed useful in the beginning, and was meant to make users’ lives easier, but which at the end of the day is so complex that the users want to get rid of it.
I used to think I was the only one who felt this way, but quite a few features like T9 often come in the way of productivity. the reason why most of my mobile gadgets are QWERTY layouts is exactly this. I cant work reliably with T9, I am slow at using the 3-press to get to a desired character and I absolutely hate SMS lingo.