I created my first ever Flex app a few months ago for my
Trivia website. It was a
quiz player which imported the trivia questions in json and
displayed then one at a time.
It only used a few basic components like text boxes, labels,
buttons yet the size was over 300kb. Using RSL's I got the size
down to 146kb, but a small few users were reporting RSL errors so I
eventually rewrote the app in Flash CS3 and I couldn't believe that
essentially the same app was now less than 50kb.
I think Flex is a nice language and would use it again for an
AIR application, but I can't see myself using it for any more