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 / database? (~/.local/share/Tomahawk and ~/.config/Tomahawk)