I've got just over 20000 KLM/AF miles, and had an e-mail regarding their Spring promo rewards for a 50% discount on the miles.
I managed to get a return flight from Birmingham to Dubai in June for 20000 miles, but it stated that Taxes, fuel surcharges ...etc were extra, the total cost of which were 428 Euro's. I haven't got a calculator with me, but I reckon that's about £350 - £370.
It looks like a con to me, as a quick search on line shows I can get a flight to Dubai in June with a good number of airlines for around £350 with all taxes paid and no need to use my miles up.
I'm not planning on going now anyway, but might have done if I could have done it for about £50 - £100.