It's pretty awesome, but it's lacking a few very important things. The first I noticed was that it has no support for saving and loading shared object libraries (SOL's), which are what pretty much every flash game used to save data between sessions. They're pretty much 'Flash cookies.'

Also, it, like pretty much every other project except lightspark, doesn't seem to implement much of AVM2/ActionScript 3, which the "last generation" of flashes mostly used. Lightspark supports more of it, but still has severe rendering issues.