Great game, easy to learn and play. When you start out, it takes a little time to get into it, you'll probably die a couple times before you get the hang of it, thus losing to stronger players all the time.
The only bad thing about the game now, which has nothing to do with the game, is there's not a lot of other players playing now. So, a lot of the people left playing it are higher levels. So, the function that controls associating people with people more close to their level, thus making it easier to fight each other, is disabled, practically. I've been on there recently, and there's usually around a 100 people, globally on, when I'm on. This is the only problem I usually find, as it affects gameplay. Without enough people, each multiplayer game has a hard time surviving.
Now, if you want my honest opinion of the game, it's great, awesome even.
I usually delve into campaign when I don't have anyone to play with. However, even in campaign I get the opportunity to shoot up a lot of cpu's so it's great.
The key is learning how to learn to use each weapon as quick and efficiently as possible and learn how to use your character as best you can. Ex. wall running and moving while shooting is key. The moment you stop running, especially in multiplayer deathmatches, you're dead. All it takes is a guy to come up behind you, or snipe you from afar, and bang, you're gone.
The loss of a bunch of people makes this game harder, as you have to face down really tough opponents at times, and there's a lot less people to have fun with. You aren't able to get through the campaign as easy, due to this, also.
My advice to others is, if you have steam friends, have them come along with you, at least when you start out. This will allow you to further both of your profile characters and gain a lot in the process.
Also, don't forget to log in everyday as you get daily rewards, as well as rewards for winning a specific amount of normal matches, usually 2 or 3. Use gold to unlock characters and weapons, mainly, although, if you don't really care what to use gold on, they have much much more to save up for.
You can spend money on this game, but you really don't have to. I haven't seen a need.
I should address, before closing, that when you start, if you're going to pick a character that'll last in a fight, and gain you gold more quickly, I'd pick either Elena or Max. If you don't care gender wise, Elena or Max is perfect. Elena's got the best for far away battles, which is a lot of times better. Max is good on offense and defense, with a massive shield built for ultimate defense and ultimate pummeling of opponents. These two are quite honestly, the best characters in my opinion, and will take you far quicker.
Ivan is often a common choice, although, he is likely to die quicker, as he acts mainly as a melee fighter. If you're going to use him, I recommend being familiar with his third weapon, a sniper rifle. To activate the scope, right click when using and you'll be able to see cross-hairs and a lot close up. On a fun note, the sniper can actually hit more than one target if the targets are really close to where you fired. However, the cross-hairs must be directly on a target, not an inch off, in order to hit.
Lastly, this is important for any new players, or anyone who is playing who doesn't know this. On a laptop, especially the newer ones, like I have a Toshiba laptop, you have the special keys which control volume and so much more. Now, when playing campaign, you have things called revival coins. It'll ask when you die to press F5, or F6. However, when you press the key on a laptop, it doesn't work, and you usually have no idea why. I only figured it out recently, that you have to press the key on your laptop named "FN." It's a little blue key on my computer on the left side in between my "windows" key and my "CTRL" key. It's on the bottom. You'll have to press the "FN" key plus F5, or F6, as asked by the computer, in order to revive.
So, to repeat, "FN" + F5 (or F6) = revive coin use
Now, just to warn you, you'll respawn in different places in the room. It'll usually be in some beginning part of the room you're in, not in the very beginning of the campaign, so don't worry about that. However, where you respawn isn't always where you want to. So be careful when respawning sometimes, as you sometimes wind up in the wrong spot and die quickly.
Alright, I think this'll do it for now. Hope this helps, and hope you all enjoy.