Niche
Depends on the niche you're referring to.
I have a Cowon/iAudio J3 (32GB). True, it doesn't do apps in quite the same way (only dodgy flash games), but it does have a really nice touchscreen, a coverflow-like system (not that I use it), brilliant battery, and great codec support.
In addition, it has microSD expansion (with proper library integration) and it can be used as a normal mass-storage device on any computer :)
And that's not even talking about the sound quality.
Unfortunately, I can understand why some people might find it a little bit techy, and even I'm disappointed with the playlist support.
Since I have an Android phone, I'm not really looking for anything more complicated than that (though, wifi file transfer would be a bonus, I suppose).