A lot of situations are, compared to vBF or other shooters, a lot more difficult to perform in FH2. Every action you do is a bit more complicated. Tanks bullet drop, use of AT weapons, friendly fire, rifle-nades, Flying without nose cam, how to use artillery etc.
For example: If you want to take out a tank as an infantryman, you can't just run up and quickly throw some packages of C4. In FH2 you need 100 years to prepare the package of explosives to be thrown and if the tank is too strong the AT weapons don't even damage the tank because you hit the wrong spot.
Then compared to vBF games, tanks are a major threat for infantrymen, and sometimes a hurdle you can not overcome. Same with some guys positioning theirselves well with a machine gun for example. There are just some certain dead zones on the battlefield. You have to search for a save path for a flag a lot more than in a vBF game.
Then another important thing is the skill with regular rifles. Some people just aim incredibly fast. And manage to instantly shoot you when looking down the sights, even on further distances. This is pretty hard to learn I guess.
I can say for sure that my accuracy improved in other fps since I play FH2 again, especially with single shot weapons.
There are some really skilled and experienced players out there, playing the game consistently for several years. Beginners are thrown in at the deep end, which can be very frustrating. Without proper map knowledge or a SL that guides you, you will most likely have problems at the start and need to overcome the frustration. Most other shooters reward you with early weapon unlocks, level ups and easy kills, FH2 doesn't.