Rising Storm/Red Orchestra 2 is essentially what Battlefield wishes it was. It's a more mature and more advanced PvP shooter that demonstrates the difference between console gaming (Battlefield/Call of Duty) and PC gaming (this game).
Many of the game modes are similar to what you'll find in Battlefield and Call of Duty, so what separates RS/RO2 is the gameplay. It's like a realistic, hardcore version of Battlefield except with much better level design, better netcoding/hit detection, mod support, and no balance issues.
Some may say it bridges the gap between typical shooters like Battlefield/CoD, and mil-sims like ArmA. Most of the gameplay, from the weapon functionality, complex vehicle functionality, and the high levels of intensity are closer to ArmA, while the scale and game modes are closer to Battlefield. Although not as strategic as Crysis/Crysis Wars or Natural Selection 2, anyone who likes PvP shooters should get this game.