Very cool, how can you not see the difference. Between high and ultra the trees look much softer and more real than the jaggery. On low there is no detail in the thatched roofs. Shadows especially on coming off the little bridge are more defined and in line with the planks of wood than on low. If you can't see how jagged low is compared to medium and Ultra then you aren't looking close enough.
As a 360 gamer I have been looking at the PC screens to see what the diff is and frankly I don't see any difference that would matter in full motion. Yes, I see the higher res textures and longer shadow distances, but when actually playing the game I don't see any of this mattering.
It's almost comical to me how folks are dealing with Steam and spend a couple hundred on PC upgrades and the consoles pretty much run it the same way. Not as high res or with the same draw distances, but 'good enough' when the game is in motion.