Have been working with Oracle Application Express (aka 'APEX') for a while. APEX gives me some mixed feelings.

Pros:
Free tool, nice for building simple webforms.

Cons:
Unfortunately a pain in the a** when building complex webforms. This is not only due to limitations that have been designed into the product, but also due to many 'features'. Finding a work-around is possible but rather time consuming given the limited debugging functionality.
Steep learning curve.