I returned from vacation in Australia one week ago, and the Great Barrier Reef was perhaps the No. 1 highlight of my trip. I loved Australia - one of my favorite trips ever, and I have been to every continent except Antarctica -- and I could only snorkel, not dive, due to medical reasons, but the GBR was spectacular. It only made me want to return for longer, and spend multiple days diving. I also recommend paying for the inboard photographer's pictures, unless you are a really solid underwater photographer with a quality underwater camera.

I spent 5 days in the area - two staying at Cape Tribulation in the Daintree Rainforest (Where the Rainforest Meets the Reef). The fact it is stinger season is somewhat of an annoyance, and it is rainy season, thought hardly rained while I was there. But there is much to see, do and explore in the region.
Enjoy!