nice demo, first of all if you have problems running it and you have avg antivir you must disable your resident shield.

now to the game, some things that came to my mind when playing... dont take it personal its just to help you make it better.

-buildingtextures need mipmaps
-trees are too transparent or hard to see against the landscape
-treefadein is too late
-most of the models and explosions look a bit ugly
-explosions are way too slow/unrealistic
-shaders are very good and fast at least here
-menu is not soo good
-the landscape is too deserted (no roads, no trash, no broken trees, no rocks? ...)
-enemy? cars drive into napalm if you place it in front of them

well, i think you will be able to get the above stuff right. however the biggest problem i see is the gameplay. you have taken a road between realism and arcade wich is a bit confusing in my mind.
you need some kind of waypoint system or objectives that point the player to the next thing to do. otherwise he is lost in the big area.

the controls are okay i would say... however i would limit the maximum distance the player can fly above the ground in some kind of auto hover mode just to make things easier... think of flying over a big mountain that ends in the ocean, you will have to fly all the way down again with this controls... whereas if you would implent autohover, the player could just press forward to fly over the mountain.

you could really turn this into a fun game, if you spice up the graphics, make the controls a bit easier and make intuitive missions(like search and rescue, defend against attacks, destroy something...)

im looking forward to the next demo! greetings