I use Flash at work for design, programming and minor animations. Flash is certainly one of the best programs ever created. If you have time, learn how to use it.
As you might know, Flash's base is vectorial illustration, animation and programming. Given that, you know how much advantage you may take. Before you decide to spend any money with training, join a Flash forum and visit sites containing didactic resources. Check what is and what is not for you right now. And learn things calmly.
Before you begin learning Action Script, learn basics of C-like programming. AS is an easy OOPL most of the time, and understanding the basic structures of C will contribute for a fluent learning, mainly if you are used to the comfort provided by Basic-like languages.
When you understand well how Flash's base works, you will decide what you will study in depth.
Cheers.