Just got the app form Ovi Store and its one of the best lookin Music Players yet..

Things I Like

1) LARGE Album ART
2) Great placement of Navigation buttons and the navigation pane on the Top
3) Portrait mode

Things I would like to see in near future versions
1) Playlists (which u mentioned is being worked on)
2) Maybe Desktop Widget? or better.. lock screen navigation buttons/song name display..
3) Using MAFW.. cos the present backend causes the playback to stutter when device is locked/unlocked with the power button
4) Stop Music Playback when Headset is disconnected
5) Search music.. An interface similar to the contacts one in portrait mode will suffice.. ie.. Have small buttons with " ABC, DEF, GHI, etc on the right pane.. Will make navigating a lot easier..

Things for later later in the future..
1) Support for Music Headset adapters such as Nokia WH-701 or Bluetooth Headsets like BH 214/BH 503
2) Landscape mode
3) Cover flow UI.. :P

As for volume slider.. i think its not a must but can be added..