Thanks, I'm glad you like it! Yeah, Flash has improved a lot recently. Its a very similar pipeline to DirectX 9 in the way you set states and then call draw functions with a final present call each frame. Most of my experience is with DirectX and C++ but my job for the past 5 years has been Actionscript programming so I was pretty excited when they finally introduced Stage3D. I think the main problem in pushing it so far is the AGAL language as its pretty inaccessible. This project was supposed to improve on that by giving a higher level language much like HLSL or GLSL that would compile to AGAL instructions. This isn't that complicated on a basic level but creating optimized AGAL from a high level language was my biggest challenge and its still not perfect. Hopefully it will still come in useful to some though.
EDIT: many typos