I have been mainly working with AS2 as most client's still prefer the larger installed base of Flash 8 players. I thought a 3D project in AS3 using the Papervision libraries would help me get up to speed with the new aspects of the language.

AS3 is a lot stricter language than it's earlier incarnations, it's class structure allows object inheritance and is based on ECMAScript making it very similar to Javascript. Programming AS3 in Flash 9 is not as easy (or the same) as in Adobe's Flex development environment as it provides better prompts and project control. But Flash is what I'm working with at the moment and so I will have to live with it and hope that Flash 10 will be better.