1. Gamma
Dark maps are very dark on some monitors, so now you can change gamma. If things are too dark, try setting gamma to 1.5 or so:
By the way, you probably want to use vsync=1, unless you have gsync or freesync on your monitor.
2. Lights
Terrain now interacts with lights
Helicopters now have a light attached to their tails.
3. Sandgun
Sandgun no longer builds instantly when pointed, but fires a projectile. This makes the gun less overpowered and the terrain a little less wonky for vehicle movement.
4. Vehicle Team Color
Teams of vehicles can now easily be spotted by color.
5. Smoother fog
The fog is now smoother and will fade out objects instead of instantly make them disappear.
6. Two hands
Finally, the character models use two hands.
7. AR3S tweak
AR3S got a pretty big change, it is silenced now and does more damage and has higher recoil.
8. Misc.
Many small tweaks here and there.