I've recently switched to proplayer and really enjoyed many of its features particularly the ratings system and autosaving of settings.
One I think is really innovative and I also enjoy using is the ShakeIt mode. Unfortunately I am having some issues with it. Although it works well upright, when the phone is upside-down, this feature doesn't work properly and sometimes goes forward and sometimes goes backwards instead (My phone still has a 3.5mm jack on the bottom which I plug into and either have my phone upside-down in the car or shirt front pocket). I believe it is because Proplayer doesn't know if it should reverse the gestures or keep them default. Due to that, when I shake the phone it has a 50-50 chance of going forward or back.
Potential solutions
1) Allow Proplayer to restrict auto rotate, that way theres no issues with the rotating of gestures
2) Allow programming of each gesture (Eg: So I could set both shake forward and shake back as advance track)