I don't understand what's so great about this map?
It's just a map that's been overloaded with foliage (which anyone could do) and that has similar lighting to the GDC demo level. Yes I have played it btw. It's not really any more impressive than the other Crysis levels (that's not to say they were bad though).
Because it gives a look into what could be acheived with the engine. When crysis was coming out the devs were talking a lot about how moving leaves could give away your position and the enemys. In the game though that never really played that much of a factor, but in a dense jungle setting like this with enemys all around it does help and does play a factor.
That and the use of lighting and depth of field really makes the visuals stand out as they were intended, after playing through this map on max settings it makes other jungle areas in crysis look very muted and flat looking.

for some reason cant print screen all very high dx10