Bumping this with major updates. Darktable has had a huge update and is now at version 3. Loads of features that are too numerous to list individually: https://www.darktable.org/ Another popular raw image processing tool named Rawtherapee has also had extensive updates. Similar to both Darktable and Lightroom, although it takes a different approach to a few tasks, so if you're not a Darktable fan (or just want to compare) give it a go: https://rawtherapee.com/ Both of those are multi-platform (Windows / Mac / Linux) so grab them no matter what your OS preference and give them ago. I'll try and find some nice feature demonstration videos and post them shortly. Linux users only, I stumbled across a pretty nicely featured photo transfer tool. Excellent for transferring and organising photos from your various devices and cameras across to wherever you need to process them: https://www.damonlynch.net/rapid/
Will have to give Darktable a go again. LR is being a pain and not interacting well with my copy of Adobe Acrobat 2017 as it keeps updating it to CS and then it requires a full reinstall of all Adobe products. While its not free/open source. Worth giving Affinity Photo, Designer and Publisher a mention. Ive completely switched over from Photoshop, Illustrator and InDesign with very very minimal impact. Yes, they do cost a bit. But for around AU$60ea they have already been paid for by the licensing fees of CS.
Darktable is great. On Linux. Have had a few issues with the windows port. And (this is not a criticism) the windows port is not particularly well supported, as that entire idea was only made possible recently, and a single dev is in charge of it. If you're gonna use it on Windows, I'd recommend a lightweight VM to do it.
I've completely ditched Adobe. Gone perpetual license of Capture One when it was heavily discounted, and bought Affinity Photo. Never going back to Adobe. C1 is just awesome.
I tried that one within the last couple months. To be honest, it seemed to have regressed in compatibility. Perhaps there's been bug fixes since.