Only a couple levels in. The running away from Koreans at night level was awful, retardedly hard D:
I think the game gets significantly better after that point, when the entire taskforce attacks the island, and it becomes a massive battle. At that point you start to get the cooler weapons (Gauss rifle, minigun, incendiary ammo for the AK), and enemy difficulty ramps up. The tank level is pretty badass as well, especially if you try to blow up tanks by foot by attaching C4 to them, that's hilariously awesome. Once aliens show up, the game gets preposterously badass, the alien ship part of the game is amazing, although it's horribly disorienting. But that's the intended effect.