I don't use it, because I like being able to see how bad things are without any additional variables. I'm not sure of the upper end, but on the low end, it's never shorter than the time taken to start Activity monitor and force-quit the 'Flash Player (Safari Internet plug-in)' process. Loading Flash content, no matter how large or small, complicated or simple, causes my browser to spinlock for any number of seconds or minutes.

So, on number one: Dismal, dismal failure. The Flash Settings and Global settings, aka, 'The Second Worst UI In Production Today.' (Notes is still worse.

The browser may not have crashed to the point where it quits, but if Flash makes it unusable, regardless of how long, Flash crashed the browser.) When my browser is not capable of functioning, that's a crash. For my uses, there were a set of specific things that made me absolutely hate Flash.