It's useless making a proper review of Flash, by now, so here's my comment... ;-)
At the beginning of 2017, I uninstalled Flash NPAPI and switched to PPAPI so that I could fire a secondary Chromium browser when needed — my main one being Firefox — and that would be an advice I'd still give to anyone using a site that needs Flash.
But on my side, even the rare sites I use that were still needing Flash a few months ago have now abandoned it.
So a few weeks ago I also uninstalled the PPAPI version, installed VLC plugin, just in case (I'm not even sure it's of any use...), and all is freewheelin'. :-)
I've never had any issue with Flash, so I won't blame it for anything — and before html5 came out of the wood, it was mandatory —, but it's simply useless now, for the vast majority of websites.
It's the haaaard law of software: essential ones (such as Stuffit and many others) end up obsolete and useless.