Work wise, as a developer I apply it a lot when I see that there is some form of miscommunication. As a developer I am sort of used to fight for my opinion in discussions but before I was not able to voice it that I was mostly concerned. For instance. I work with startups, and the founders talk a lot in meetings, but don't really seem to listen to clients want (because they are passionate of their product/idea_. Instead of saying you should listen more (actually I did this a lot in the beginning), I'm voicing that I'm afraid we're missing out on clients and we should work on a way that we can ensure that clients feel heard.
In the beginning I was a bit unskillful, so I weirded out some people, but it got better over time. I don't really use the template as-is anymore.
In terms of failures. It's a bit of a balancing act in opening up and vulnerability. If you apply it properly you're basically an open book, and not always the people opposite of you can return the favour. There will come a moment that the person opposite of you can't open up just yet.
I still think NVC is a good base to start from. On top of this I also started practicing deep listening in the practice of Buddhism at Plum Village in France which also helps me in life.
It takes energy and practice and it will always be work, but I see it as a good addition in my life.