Two weeks ago, we evaluated whether we ditch our current proprietary EDA tools in favor of KiCad (my company designs and builds satellite electronics). We liked the user interface (it's not good, but better than the "professional" alternatives), the gradual learning curve, and the plain-text project files. Plus, we're big fans of OSS.
But KiCad has a lot of conceptual baggage: The way tracks, vias and copper zones are handled requires work-arounds and band-aids even for routine tasks (this has been known for two years at least), with not simple fix in sight.
The PCB editor has three display modes: Legacy, OpenGL, and Cairo, with different features (unrelated to graphical representation) available in different modes, so you have to switch between them from time to time (this also hints at a lack of separation between graphics and program logic).
There's a bug that prevents laying tracks closer than 0.2mm to each other (only in OpenGL mode – Legacy mode doesn't care). The "Clean-up tracks and vias" function deleted some definitely non-redundant tracks, which I only noticed thanks to the DRC (though a DRC cannot and will not catch everything).
Our conclusion was that for hobby projects and very simple professional PCBs, KiCad is a great tool, but it's just not enough for even slightly demanding projects (and I'm not even talking about high-frequency design, EMI analysis, and multi-person projects).
The developers seem to prefer working on interesting new features like the push-and-shove router, instead of fixing the basics. Which is fine – it's an open-source project and they're entitled to work on whatever they feel like. But unfortunately, this is not how you get to a "mature tool". I wish them all the best, and we'll take a look at KiCad again from time to time.
Preemptive reply to "why don't you contribute to it?": We thought about donating to the project, but the amount of money we spend on professional EDA tools per year would only buy us about 10 day of KiCad developer time (or in-house developer time) – by far not enough to fix all show-stoppers.