If there are two things I disliked about the game, they would have to be the plot twist (not the girlfriend related one) and the last boss. A shame to be honest, since I really liked the rest of the game.
Exploring and trying different gameplay approaches. The one I've been doing lately is combining a maxed out sneak skill with a Chinese stealth suit (Operation Anchorage DLC). Which in effect makes me completely invisible regardless of the outside factors. I can be sitting right in front of the mutant overlord and play radio while having my flash light on and he'd have no idea I'm there. Headshots from stealth are some of the most satisfying kills I had in the game. Also I personally found some of the best quests in the game to be outside of the main story arc.
Korean web portal DC News did a phone interview with the publisher. "Debating (as to if it's a rip off or not) is like having blind men touching an elephant and describing what it looks like," said SK iMedia. "We will reveal the gameplay soon. Other than that, we have no comment at this time."
I'm a little surprised that this trailer is aimed at the western gaming market (what with the english voice work and all). Come to think of it , the likeness to TF2 (which to me seems undeniable) might actually be a marketing move, to a degree it worked, I did see this on a number of news sites (though never in a positive light). Any publicity is better than none I suppose. Though I might just be giving them a little to much credit here.