Darktable

Not only Darktable but Darktable paired with digiKam, :)

I looked at it. Seriously, not even close to LR.

Pretty much the case for Linux boosterism outside the command line. Almost every desktop app is a shoddy imitation of a commercial app, pushed by people who often don't know the real apps.

And if you point the shortcomings out, they whine that the shoddy app is only built by three guys and so it's unfair to judge it...