I really like the concept, but the software is totally broken in Linux. Not even adding files to a playlist works. The song names are in the playlist, but the files can't be found. The program crashes every time it's closed. And there's a problem with the default Ubuntu theme: Selected menu items have white text on a white background. A few patches and it could be a great player.
Thanks for the kind words. We've fixed the problem with the default Ubuntu theme and also have a bunch more design improvements, as well as general bug fixes which you can find in git (stable-0.8 and HEAD). Not being able to resolve tracks at all sounds strange, though. Right now I would guess it's either a corrupted database or index. Could you try and see if you can reproduce the issue after wiping your settings /…
Opening every album seperately with the arrow icons and dragging the songs directly into the playlist mostly works.
Dragging the mouse to "local" when adding to the playlist seems to work better, although it will still fail to add some albums, but I don't get all the greyed out entries (I think many of these are from automatic online sources, even though I don't have any online sources configured). The behaviour is definitely weird.