a couple of my friends have done it. from what they told me it is tough but if you don't get it the first time you should be able to get it the 2nd time but if you don't get it then they said you'll definately pass by the 3rd time you do it.
but i think most them them did it in their first or 2nd try. they did it at school because our high school allowed us to do it even though it didn't count towards our hsc. i didn't do it but i think most of the people in my year that did some sort of computer course in year 11 or 12 did it and passed without too much stress.
good luck if you decide to do it. i'd advise you to do it because you can get a lot of work out of it.
Go the aussies! stosur!!!
and good luck russians: dementieva, safina, kirilenko, sharapova, kuznetsova, bovina, zvonareva, dushevina.
also good luck to: azarenka, lucic, sprem, vakulenko, vaidisova, safarova, ivanovic, groenefeld, mirza, krajicek, kvitkova, larcher de brito, lisicki.