Eddie Lopez has written a good post about the usability problems of the iPhone and iPod Touch interface when listening to podcasts: Design Decisions: iPhone (focus on podcasts). The problems he discusses are these (see his post for detailed description and recommendations):
- The volume bar is in a different location on the locked screen.
- The slider for controlling position within a track is inadequate for long podcasts or songs.
- Pressing and holding the forward/back buttons to scan forwards and backwards is difficult and unreliable.
As a user I agree that these are problems, though I don't think #1 is very important. It's an issue for initial/early use but is not likely a problem for experienced users, so I think it's okay given that they probably had other reasons for rearranging the home screen when the device is locked.
The iPhone sliders are something I've thought about before. I find them awkward to use because my finger is in the way. This may just be a strange personal quirk, but what I tend to do in order to adjust them more precisely is to grab the slider and then slide my finger up out of the way before I change the volume by sliding left and right. This way I can watch the little ball move and it feels more precise, even though technically it isn't. I'm happy that the interface supports this interaction (it could instead lose focus on the slider when I slide my finger up away).
I'm interested in this kind of invented pseudo-gesture because I imagine it happens frequently. It's kind of like the notes people put on interfaces to improve them (and other input device workarounds), but it's more subtle than that. The notes probably make a measurable difference in performance but my invented gesture is more of a perceptual or emotional thing. Are there other habits like this that we invent to improve our interactions with devices?
Back to my volume-slider gesture, the interface could make it explicit that you can interact with the slider in this way, though I'm not sure if that would be a good thing. When you touch the slider the ball could transform into a rolling pin. Imagine something like the following but drawn better. Would this be an improvement?