While I haven’t been the #1 fan of the Lightning Design system and some of the UI/UX inconsistencies that exist across the platform now that Lightning has been rolled out, I’m actually a big fan of the Process Builder.
I’ve had a chance to plan out some projects, utilize Process Builder to build them, and then sit with clients and actually have a graphical way of explaining and going into detail about what is happening at each step of the process.
Best of all, it’s allowed us to remove a bunch of difficult-to-understand workflow rules and integrate them all into one process.
It’s not without its bugs; there are some oddities around scheduled actions blocking lead conversion, and some things that workflow rules can still do more effectively. But with the addition of invocable Apex classes, there’s a lot of good things you can do now and I’m sure that the coming releases will only expand on that.