Where do I start...
Graphics:
Looks poop out of the box in Vista, looks better and runs faster in DX9 mode with custom tweaks. But it's hacking. It shoudl be stunning and running much better with default settings
Weapons:
Two shots from Bauer 1980 SOCOM Pistol (named after Jack Bauer undoubtedly) can often chop down a palm tree from 500 yards even with silencer. The same gun, from the same distance can be fired up to 20 times in legs and torso of the enemy before they get annoyed enough to move somewhere else or hide.
FY-71 rifle in burst mode has less power than two single shots from Bauer handguns with silencers.
Up to 1000 yards reflex scope (the one with red dot) is better for headshots than assault or sniper scope. You only have to roughly position red dot around enemy head and you have certain, guaranteed headshot, whereas both assault and sniper scope dance around long distance targets like a one handed drunk sailor spanking his monkey with binoculars to his eyes.
Removing 5 out of 6 beams propping any roof will not cause that building to collapse. Regardless of size.
Frag grenades shot from the FY-71 rifle are about 10 times less effective than hand grenades. You have to hit enemy almost literally on forehead for any effect.
AI
AI is just daft - enemy will see you in bushes, point at you, run to raise the alarm, often even shoot a petard and then... start sneaking in exactly opposite direction with their back to you.
Once shot the enemy will often look for the source of bullet for exactly 30 seconds and then forget about ever getting shot. Must be natural occurance in Korea.
Helicopters can see you regardless of how deep and low in the forest you are. Sometimes you are hidden so deep and so well that the bullets of their guns can't reach you, but they will still spot you.
Machine gun positions are guaranteed spawn points. Once you shoot a gunner the nearest AI soldier will move on to replace him. On some maps you can camp long enough for the bodies to pile up to the point that 10th or 15th gunner in a row simply can't reposition the gun because of all the corpses.
Body with pool of blood in the middle of the road does not alarm walking guards. They will walk by and let you shoot them point blank from behind the same stone, no problem.
Enemies cry "Grenade!" and then start running around it in circles.
Physics:
Blasting semi burned out buggies with grenades will often make them explode and dance around with rumbling sound and metalic banging for long minutes.
Some objects, like frogs, when thrown will fly forever.
Guns and bodies get stuck in hut floors
Objects levitate in badly coded areas - weapons, bodies, shoot all tyres on trucks in quarry and they just stay, floating in the air. Chopped down trees sometimes prop themselves on two straws of grass.
None of which would bother anybody if it wasn't for the fact just about any reviewer of this game peed their pants about AI, graphicsm, physics and realism of this game.