ND2D has some obscure gotchas, but in overall use it's pretty straight forward, it's not a million miles away from the display list.
One thing I've noticed though is that it doesn't pool internally, so it's very wasteful ( I've ported DN8 to Android, and it doesn't run too bad, but I'm slightly concerned about the memory leaking away ).
Where I've got it running with away3D I've had a good hack at the code to try and tidy up what I can, but there's a point of diminishing returns. The GPU particles for example, they may run quickly but they create so many objects to get them running. Fine for something like a fire effect, but for explosions they're not really usable.
( I assume the GC kicks in and sorts most of this out, but that's kinda random, and it's the last thing you want when running on mobile ).
Also the change in workflow is a shock to the system, having to use things like TexturePacker ( Which is excellent btw, well worth looking at ) and making sure all your sprites are the right size.
I'm trying to knock my own framework up, it's just a case of finding the time, when you're indie you don't really have the luxury of R&D, everything has to have a fairly sharp-ish payback.