As a Plasma dev, honestly, we couldn't feel more different right now. I've been hacking on KDE for 12 years now, and this year has been one of the best. Here's where we're at:
* We're about to ship Plasma 5.8, which will be the first LTS release of the Plasma 5 product. It's been an incredibly satisfying dev cycle, where we really hunkered down and spent a few months on performance optimizations, robustness (especially around multiscreen) and fit and finish (our design guys did an awesome job). There's not a doubt in my mind that this is the best version of the KDE desktop we've ever released.
* We've significantly professionalized our engineering/process story in the last two-three years. All of our new code has really high test coverage, we're increasingly expanding test coverage of our older code, we've got better habits on code review, we've got real meeting cycles, etc. I'm pretty confident about calling some of our new code best-of-class - e.g. our kwayland lib is the best-tested Wayland implementation around, period.
* We've been able to do the above things despite having ongoing porting churn (the Wayland transition), which is a process challenge we failed pretty badly in the past (the KDE 3->4 transition). We've learned a lot about how to manage ourselves, and most of the work we've done for Wayland has directly improved the quality of the X11 experience as well. Every time we've had to rewrite something we've asked ourselves what other goals we can hit at the same time that deliver concrete value to users.
tl;dr We think what we do now is the best we've ever done, and that we get better year-over-year while living up to our original goals. And we're not about to stop.