I think Darktable fits the mold of a lot of other good free software in that it's well features and probably does what you need it too, but the proprietary equivalent(Lightroom in this case) is a more polished and easier to jump into, or at that's what I got from trying to introduce both(along with I think LightZone and a couple others) to my wife and she was just better able to pickup Lightroom. But if you want to move to Linux and take the time to get to know Darktable, I think it'll ultimately be a good replacement.