In short: Generic modern military shooter #123781 that completely misses the point of idiosyncrasies of the one thing that somewhat sets it apart from the rest of the bunch: The fact it is set in WW1. Look at Medal of Honor (well, it's WW2 and therefore somewhat of a Nazi popper, but what do you expect) for a decent WW shooter campaign; I actually don't recall any significant WW1 shooter at the moment...
And as someone who is decently competent in competitive shooters (~2000 hours of Counter-Strike Source): Yeah, competition can be fierce even on "normal servers", but if you can keep up you'll get rewarded for it with a mixture of familiarity and challenging gameplay. And playing in "rough environments" has battle-hardened me I suppose. Dieing 10 times to superior opponents in a row barely moves me at all anymore, so if you don't get discouraged too quickly you may well find your frustration will wane with time.
I think it breaks down into a few categories;
1. Excellent controls. Probably the tightest and least obtrusive controls I've used in a long time.
2. Great characters. While the story itself isn't that great (because it's unfinished), the characters really drive the plot.
3. Amazing ambiance. I really felt that I was in Afghanistan and there were Russians I was trying to avoid. I eavesdrop on their conversations, hearing them yelling orders to each other, and even see them adapting to my tactics between missions.
What makes this game a great single player campaign is ... Weight. Everything has consequences because you care about the characters. Most AAA games don't have characters anyone remembers or cares about.
This is failed design. I eventually gave up on Call of Duty because while the control and bite-sized (multiplayer) games were great, there were such fundamental flaws in skill matching and team-work that it was un-enjoyable once the novelty was gone.
I compare this to Overwatch and hope games will continue in this direction. Matchmaking is much more balanced and team-work is far more important. It still has a long way to go, especially in rooting out toxic players and making it easier to spontaneously group with players you like -- but its an improvement and hopefully a trend that will continue.
Because of the objectives, it is possible to contribute even if you aren't getting tons of kills and the game as a whole felt much more balanced than CoD. Even if the other players are much better, you can still get a few kills in and help your team.