I really like this series, so it's a bit of a shame that it looks like this will be the last. The simulation nature of the game, where taking fire can be quite series and result in the quick death of a team, as well as the large, varied maps, mean that it encourages smart gameplay over a "run and gun" approach. As such, the team games become quite co-operative, with each role - there is a sniper, a heavy gunner, a rifleman and a semi-automatic specialist - needing to focus on a specific task. And you can change mission to mission - I remember playing one where we had 2 snipers, and 2 rifleman, defending a fort against waves of attackers. The missions are also impressive - they feel undercover, and each of the tasks you're given seem believable and you can undertake them as you see fit. Whether that's as a long range sniper, or by a more cover and rush technique. I really like the 'hardcore' mode, where once you die, you sit out the rest of the game. Encourages proper teamwork, and covering the person whose looking at the map ect as the minimap is disabled. And where you can't see your stats or bullets in this mode too, you need to be aware of your ammo, and look out for the tracer shots (the last few bullets in a mag leave trails)
Pro's: Hardcore mode - a good test of what it's like to be in the field, and can create some real excitement. The realism, some FPS have become rather silly in recent times. The large maps. Working as part of a team of 4 (those not human, become bots which follow orders issued by the 'leader') The encumbrance system as you take damage to limbs.
Con's: There are set types of enemies, which detracts a little from the game. Vehicles are disabled, which is a shame as they were included in previous versions.