Is not as bad as I always say it is. I complained about it a lot because I wanted it to solve a very specific problem I had with laying out rows and columns of elastic width elements on a page. But it doesn't solve that problem. As far as I can tell.
I had a job for a while where I was restricted from using the latest features of CSS for compatibility reasons. I often thought, "Ugh, FlexBox will solve this." about a particular problem. But I hadn't used it. So when I finally got to, I tried that, first thing. I was a little mad.
Basically, I thought with FlexBox , I wouldn't need media queries anymore. Because I still did, I found FlexBox useless. Now, maybe I was just using it wrong, but regardless, I do use it now, and prefer it to the old inline-block or floats method of laying certain things out. Even if I still need media queries to shuffle things a little for narrow displays.
I used it for the older/newer posts buttons at the bottom to push them to the edges. I think it required a little less work than it might have. Or maybe it just provides a nicer mental model to think about the layout. But either way, I'm over my cynicism.
For FlexBox anyway. CSS could always be better.