Moock says no (no harder than 2.0 or 1.0)
As a developer who’s been using Flash since it was known as FutureSplash, I simply can’t find any good reason to avoid ActionScript 3.0. I can still use it on the timeline for simple scripts, I still find the basics pretty easy to learn, and I don’t find it demonstrably more verbose than ActionScript 2.0 or ActionScript 1.0.
On the contrary, once I started learning ActionScript 3.0, I found programs faster to create and easier to maintain because of the cleanliness of the API and the coding assistance available in Flex Builder.
I’ll add that as an AS2 project grows and grows it gets harder and harder to handle mainly because of scope issues which are solved in AS3 (RIP Delegate.create). I also never want to throw my computer out the window when adding children in AS3 as I often did when attaching movieClips in AS2.