BROWSING THE LIBRARY
By now, when you browse the library, it's only possible to filter according to artist and genre.
However, in the Auto DJ screen there's a very useful option that takes advantage of Last.fm similar artists. So, why not using it as a browsing library element?
For example, imagine you feel in the mood for some Alanis Morisette songs. Then, instead of going to the browser and filtering using Alanis as artist, you filter using as condition 'Artists who are at least 1% similar to Alanis according to Last.fm'.
Difference with the Auto DJ is you're not getting a playlist, but the library filtered by similar artists.
NOW PLAYING LIST
By now, it's possible to place the now playing list in the central pannel, the right and the left one. But the moment you place it in one side it disappears from the other ones.
Is it really necessary? What it means, it would be great to have it in the left pannel to drag and drop songs, and to have it in a tab, in the central pannel too, because it looks better when playing the songs.
By the way, in the left pannel there's a button, 'Show library explorer', which makes very easy to swap between the usual left pannel and the library explorer. Why not having something like 'Show library explorer', 'Show now playing list', 'Show usual left pannel' that allows to swap quickly among them if you place the now playing list at the left pannel?