Got this free on Steam. You should have done so too. This isn't entirely realistic, but it's one of those games which strikes a balance between realism and fun. It's challenging too. The story, however, is not very engaging. You are an OSS agent in WWII trying to assassinate German scientists before the Russians can get them, so not only will you fight German soldiers, but also Soviet soldiers. And there's was a lot of room to make a decent story; you are a secret agent carrying out missions that "never happened" after all. But anyway, on the the gameplay itself. As said already, it's great. Since you are a sniper, close combat is discouraged, and even though you have an SMG, it has limited ammo. For the best experience, I recommend you set the enemy skill to "Veteran", realism to "limited", and tactical assistance "off". Lower settings to me make the game too easy. That said, you have to praise Rebellion for making customizable difficulties. And the main feature of the game: the X-ray cam. It show just what a sniper bullet can do to your body. Can be quite satisfying, especially when fighting difficult enemies. This is cinematics done right. Fortunately, if you are squeamish, you can turn it off. Also, never underestimate a single foe: he can kill you easily. Speaking of the enemies, while they can pose a challenge, the AI could use some improving. This is evident when you see German and Soviet soldiers fighting each other; they will have no problem trying to kill you, but they seem to not cope well when fighting each other. The campaign has a decent length: 8-10 hours. And a second play-through is worth it. Multiplayer is quite fun too, you are all snipers. Element of surprise and awareness play an even bigger role here.
So do I recommend this game? Yes. But you should have got it when it was free. Right now, it's $30, and I don't think that's a good price. If you didn't get a free copy, wait for a sale: this game is worth $20 to me.