The catch is you have to fly Ethiopian Airlines. I recently flew from Botswana to Washington, DC via Addis. This was the absolute worst service and transfer I have experienced in my 64 years.
The bathroom by the end of the flight was absolutely full of nasty toilet paper, the sink was clogged, and the trash can was overflowing. This while the flight attendants sat on their jumps seats playing on their phones. Not once did they clean the toilets. It was so bad my wife just waited until we arrived. I wish I could post a photo.
Transfers in Addis are absolutely pathetic. You deboard and are immediately put in a huge long line to go through a security screening. Hell if I know what they are doing as we had soft drinks in our bags which they either permitted or simply did not find. Then if your connection is to the US you will again find a long line for yet another security screening. And again soft drinks are not a problem. Ethiopian permits 50 minute connections but good luck making it.
I honestly do not know how anyone can put up with such a garbage airline. Those who "win" this competition better be able to use their miles on a partner airline!