Just wanted to comment, but the Free Aim is incredibly useful. I've killed Mammoth Tanks using a Nod Buggy on many occasions, simply because I could use Free Aim to aim perpendicular to where my vehicle was facing, and driving around the Mammy. Free Aim let's vehicles fire at targets without changing from their track - regardless of where that target is in relation to the player. It also greatly increases the turret turn speed, when trying to chase down targets scampering to the far left or right. It let's you watch your back so you know if you need to dodge, and let's you check around corners without putting yourself to undue risk.
In terms of Orca VTOL/Apache Helicopter fights, Free Aim is almost a necessity, as it let's you move completely irrelevantly to the target, which means you're not going to immediately die just because you decided to kill an infantry. Without Free Aim, the Apache/Orca has to be lined up with the target, making it rather simple to shoot it, but with Free Aim, the Apache/Orca can come out from cover, firing at targets to the bottom left/right, and slip back into cover, without giving even a moment of undue vulnerability.
In terms of MRLS, Free Aim allows the MRLS to fire backwards, giving it more height and potentially hit more targets. Firing backwards is useful for trying to hit units hiding behind a large rock, as the rockets will arc downwards.
Just a note from your friendly lunatic Chaingunner. Causing severe mayhem amongst all nearby infantry targets since 2003.