Let me guess, your trying to get into the Masters of Accounting at the UofT? Anyways, I guess how hard it is depends on how well you are prepared. My friend made it in the first try though.
Plus according to there website, 21% of the writers are take the test more than once a year. Of these people 28% are repeat writers. With a variance of 500 to 540. The mean gain between tests is +30, but it is just possible to go down. Lastly, you can also take it up to five times within a given year.
For more statistics, check out their website
gmac.com