I am so happy that I can barely contain myself. Hopefully this means Flash will now be used for important things, instead of shoving ads in my face that I can't dismiss, and follow my scroll bar.
Well, it's true that JavaScript- and Canvas- powered ads are harder to distinguish from legitimate web content. But the flip-side is that they're (re-)programmable using standard JavaScript APIs, and thus vulnerable to manipulation by browser extensions in a way that Flash never was, being a proprietary binary format.
I can't even imagine how many hours I've lost to Flash-induced beachball. Some pages have dozens of little advertisements and assorted trash that take nearly a minute to sort out.
Any effort to make the browser experience smoother is a good thing!