The thing I liked and still like about dedicated (audio) media player devices is physical buttons so you can have non-fiddly control while it's in your pocket, and it's responsive. With my phone and bluetooth earbuds I have to either pull out a 6.7" slab from my pocket and unlock it to adjust anything complex or get the right morse code tap on the exact right spot on an earbud and deal with any bluetooth delay (I find it a blessing if the phone is oriented in the right way where I can use the vol +/- buttons).

Where I think they're missing a trick is trying to imitate the admittedly iconic iPod classic design, especially when no one is building around a hard drive any more.