Ragnor alerted me to the arrival of the demo. Many comments have expressed concern its all graphics and less gameplay, but I have to say that the engine really does complement the game itself. The environments are extremely interactive! If soldiers are creeping around in the foliage for you, you can use your ears as you could in farcry but can also spot the moving bushes. Trees collapse around you if you're under fire. Or indeed you can punch the trees down yourself. I mean literally punch them down. Entire makeshift huts collapse under large pot plants propelled under strength mode. As I told KF, I threw a chicken at a soldier and then shot him in the face while he flailed under a cloud of feathers. Once you learn how to make use of the nanosuit you can have some good fun.
I don't think I need to mention how incredible the engine is, but even after the vids I've seen I was still majorly impressed by the realtime shadows of the swaying palms and the very realistic water and its waves moving stuff along the beach.
I have to play it on 800x600 with many settings on medium though. I have textures, shaders, water and postprocessing effects on high. As I have not got Vista, it's all Dx9. It looks brilliant even on those settings, so up high in dx10 should be stunning.
Download it from Filefront.