What Apple Mail does here is to only enable the more complex formatting options if they add information that can’t be represented in the less complex formats. By default mails are sent in text/plain with the format=flowed option to let the reader know it can safely reflow the text and no HTML alternative is generated. If something that can’t be represented using format=flowed is included in the message then a HTML alternative is generated – transparently and without user intervention.

This is good partly because it’s nice to see format=flowed used, it’s a nice technical solution to the problem, but mostly because it’s great user interface design. Most Apple Mail users will never notice if it is or isn’t generating HTML e-mail, they’ll just see that it’s doing what they expect and won’t have to deal with an option that they probably don’t understand or have much of a view on. Other users won’t be troubled with HTML generated by Apple Mail users unless there is some content in the formatting. It’d be good to see more MUAs implementing similar behavior, at least optionally.

Where it falls down is in the music player. One problem is that the controls aren’t consistently in the same place and have no tactile feedback. Worse, unlocking the device when the controls have been idle for a while requires a relatively complex operation (either a treble click of the home button or swiping a software unlock control across the breadth of the screen). This means that if using the Touch isn’t your sole focus, for example when listening to it in the gym or walking around town, it is intrusive to use, demanding too much attention. Even for basic operations like pausing or changing the volume you need to look at it to find out what controls are available and where they are.

It’s an interesting direction for user interfaces but I don’t think it works for a device that should be unintrusive.