At present, I'm just looking at it to see if it's even worth bothering, i.e. does it do anything I can't get from Vuescan and GIMP -- and I was hoping to learn that without having to learn an entirely new interface, but that's clearly not going to happen; Darktable requires me to learn it to have any idea what it's actually good for. Oh well, I've got hundreds of hours to spare, right?
But yeah, lots of programs are way behind in the repositories, because of the vetting process -- security and reliability testing to extreme levels before they go in the standard repos. If I like it, I'll go look for the current version (as I did with GIMP, to the point of installing Snap so I could use the current Snap version instead of the last version packaged in .deb). Not a big fan of Snap, actually, because it makes it hard to do things like add brushes.