Here was my impression of playing War Thunder's free version.
In the air:
You begin your experience in the hangar, going through a forced training curriculum that is pretty boring. Then, unless you pay extra, you start out in an open cockpit p-26 with 2-.30 cal machine guns, and you proceed to get slaughtered by other players in 109's and 190's in a timed, restricted headcount arena. Then you either earn your way up the ladder to a good ride, or you pay extra to get a good ride.
On the ground:
You begin your experience in the hangar, going through a forced training curriculum that is pretty boring. Then, unless you pay extra, you start out in a rusty T-24 tank that fires 45mm rounds, and you proceed to get slaughtered by other players in panzers and tigers in a timed, restricted headcount arena. Then you either earn your way up the ladder to a better tank, or you pay extra to get a good tank.
Also, the best I remember, you pick your nation ahead of time, so you restrict yourself to Russian iron or German iron, etc, versus American iron, etc.
But hey, the graphics are awesome.
Oh, and sometimes it can take 15 minutes for you to get assigned to an arena, based on your country and air/ground selection. In the free version, you can't just up a tank or a plane or jump in a gun and start fighting.