I'll be the first to admit this test was a LOT harder than I ever anticipated. But in taking it, I can now see why most developers dont have a certification, and why they are not really indicative of how you are as a developer.
You have to have a complete understanding of how SQL works (which you would expect). However, my chief complaint about the test is that there are questions that dont really have any purpose on a test like that.
For instance, I received 3 questions about running iSQL PLUS. Have I ever seen iSQL PLUS? Hell no. Do I know anything about it? Of course not. Does it make me any less of a developer? Of course not. But I had to guess on those 3 questions, which meant I had to be certain I got 3 other ones right to offset it.
I never took the PL/SQL test b/c I got busy with work, and frankly, I think my work speaks more highly of me than a piece of paper from Oracle. I wish they would restructure the test to be more realistic, instead of asking questions about useless features, or features that 90% of the developers in the world dont even know exist.