How does this compare to Firefly Adventures: Brigands and Browncoats? Any one already owns the latter?
I don't own Firefly Adventures, but took a quick look and the games seem quite different. The biggest difference is that FA is co-op only while AoM has both versus mode and co-op mode. The system of FA seems more traditional where AoM is something new.
Both seem to be good for beginners but my guess based on what we know so far is that there is more game from the core box in AoM.
If you want co-op game both games are an option. If you want to fight against your friend in versus mode AoM is the only option.
Hope that helps.