A very minor observation:
The rating stars in the player panel behave differently from them in e.g. track detail view.
Suppose a track has a three-star rating. When in track details you hover over the stars, you can dynamically see the stars changing when you e.g. hover over 0, 1, 1.5, 2 stars, etc.
In the player panel the stars will only dynamically show the changes for higher ratings, but not for lower.