I don't have a ton of time with the ovals, but I particularly like that you don't need tools to put them together, and that you can change the sidewall heights.
Whenever my box stove gives up the ghost or I make it a priority to get another stove I will be getting an oval.
I don't have a Kifaru Oval but I do have a Seek Outside large Ti Stove and can setup the stove in less than 5 minutes without tools of any kind. I've never used a Kifaru Oval stove but I have to say, I like the ease of setup, adequate cooking surface and warmth provided the SO large stove. It works really well in my SO 6-man tipi.