I would describe the exam as pretty "straight forward". Many of the answers are "intuitive". However, read the material that is available either online or from Transport Canada (Safe Boating Guide) and you will very likely "ace" the test.
As far as 2007 goes I haven't heard about it. Last I heard it was by 2009 that all operators of pleasure craft of ANY size will require an operators card.
I heard that the exam format itself may change sometime in 2007 - although I cannot confirm that this is in fact true. You're correct that by 2009, all operators of pleasure craft will require a card.
On occasion, I may rent a small motor boat to take out onto a lake (e.g. Heffley Lake is large and requires a motor boat to get to the "hot spots"). The boat rental people will be asking for the card. In the past, I was able to go through a boat rental safety checklist with the guy running the resort. It's just nice to have the card now.