the key issue isn't screen size
This is the third generation of sound devices making progress, only to be hijacked by visualists. The useful functionality, which could be used for good sound playback, is piped into pictures, and handling or listening suffers. Why is a 4 inch screen better than 3 inch one? Why not wait for a 21 inch beauty? Or why not get a media laptop?
These things are all much better than tape walkmen. I enjoyed the step-up that the Shuffle brought, even with the earbud headphones, I'm moving on, for two reasons mainly: I'tunes has lost its simplicity, and the useful USP file access has been blocked by my IT department.
What had good sound, and is simple and enjoyable to use? Philips, as a hi-fi company, had a chance, but the enhanced MP3 playback of Creative or Sony made the front running - I ended up getting an X-FI.
OLED, cameras, bluetooth etc, are a risk of distraction from the main job.