Pondering on AJAX and Flex

After working with Flex and AJAX for some time I feel like looking back and asking myself when I should use what. My opinion is this:

I think AJAX, more specifically yui, can be used for most of the web-applications. It is simpler to use and written pretty well.

However if we need controls with interactive graphics/charting data or we have a very big and complex application, flex would be a better option.

Lets face it, flex is more powerful and easy to develop (and maintain) of the two. However it has its learning curve and people with good flex skills & strong programming basics are not that easy to find. If your application is indeed that complex and demands a high degree of interaction and/or analytics, flex is a wise decision. Else it is like using a hammer to kill a fly. It is good but you dont have to use it if you dont need it :).