mmpc (as installed from the application manager) does not have eyecandy (its main interface is 4 fat buttons, and a scrollbarred playlist) and does not make my tablet look slow.

So maybe you know about it, and don't consider it a "decent" music player, but your characterization "They all are full of eye candies *but* they are all pretty heavy and give the feeling that the n810 is a very poor and slow machine" is completely contrary to my experience of mmpc. I think you seriously overgeneralized your reasoning, even if you did reach the same conclusion about mmpc.