The day I decided to learn Flex SDK
Is it worth it to learn and develop for the flash platform? That is the first thing that comes into my mind about flash. In my opinion yes, because there are still things that can't be done in a regular html/css/js even HTML5.
One thing that is bothering me is, building flash application require you to understand timelines and ActionScript(AS). Being a programmer like me is not inline with timeline method of doing things(That is for animators.), Not until I saw this Flex SDK which enable you to use mxml(xml based language) to build your user interface and program using ActionScript. Some of you maybe familiar developing in the .Net platform using visual basic or other .net language its the same concept.
Web development is complex, projects may vary on its scope but being prepared to adopt is one of a great developer attitude. There is no development tools that could cater all your needs, who knows if someday you will need flash in your application al least your prepared.