I was building a website for Digital Point Ads, and for what I wanted it to do, I figured Flash would be the way to go. So it was built, and worked fine in Flash.
The problem is that I’m an anal perfectionist and the Flash object was eating 80-90% of a computer’s CPU when being viewed… and me being me, I couldn’t just be okay with that.
…so I rebuilt it with CSS3/HTML5/jQuery. It turned out much nicer in my opinion, only uses about 1% of the resources that Flash needed and as an unintentional bonus, it works on things like iPad and phones/computers without Flash support.
I’m not anti-Flash (as I said, I *wanted* to do the site with Flash), but I AM anti-inefficient. There are still some things you can’t do with HTML5 that you can do with Flash, but those things are becoming fewer and fewer it seems.