i used this toolset on almost 5 projects in my career and surely it was best time, where i learned decent development. actually at that time, there were less comparable choices. Still i beleive there are many, which provide that many features with few clicks. i mean, simple graphics, animations, transitions, sounds without being worried with small file sizes etc. more, i wasn't worried that it will work on mac or windows. super cool stuff was, application deployed was able to upgrade it self, as i put new build on server. i mean, that was awesome.

Cross platform, one code and deploy everywhere. The same codebase can also be used in web browser.

It's easy to use and it's very time/cost efficient. Building for multiple platforms saves great amount of time. Also using animation tools (Flash, Spine etc) allows to quickly build nice UI and that's a pain in other technologies. Also using Adobe Scout for profiling Adobe AIR apps helps a lot.