I've been a QFF for about eight years, and have accumulated about 60% of my points through credit card spending (always paid off in full every month - no interest charges). My irregular flying has never seen me rise in status beyond the basic Bronze.
But, in that time I've burnt points flying my wife and I Economy Sydney-Los Angeles, Sydney-Singapore for a long weekend, Sydney-Hong Kong for NYE (booked on Boxing Day) and Sydney-Perth Business Class.
They key is to be flexible with timing of travel, or your destination. Having said that, I've been lucky enough to travel where and when I've wanted to.
My only other FF membership is with Emirates Skywards, and the difference to the QFF program is amazing. My only flights with EK were Perth-London in Business nearly three years ago. On the third leg of that flight they upgraded me to First - way to build loyalty! As the points accrued from those flights were about to expire, I burnt them on a weekend trip Sydney-Auckland. EK are having a 'sale' on the use of points on some of their legs (discounting the points required by 50-60%), so my wife and I were able to travel Business Class. We booked 10 days prior to travel, and seats were available in all three classes, a sign I guess of Emirates being the new kid on this route. I was able to book with an Emirates consultant (Qantas now charge points for this, I believe), and was free to make any changes to travel dates for the next year, again for no charge. Part of Emirates' service on paid Business and First flights is complimentary limo tranfers on departure, arrival and return. They even offered this to me as a 'non paying' passenger, saving us over $200 on taxis.
My impression of the two different programs: Qantas requires flexibility, long term planning, knowledge of how the program operates (thanks to the members of this forum!) and maybe even the balls to wait until right up to your travel date in the hope that last minute FF seats might be released. Emirates: book 'n' go. Even if all their FF seats are gone, you can pay a premium amount of points and still get a seat in Economy on the flight you want, as long as the flight is not totally booked out with paying pasangers.
Levels of service are another story all together.