Not sure if this has yet been addressed, but here goes...
New Feature(s)
A semi-transparent compass on the HUD that you can toggle on or off.
Additionally as semi-transparent map on the HUD that you can zoom in or out, scale the size of the on-screen map, or toggle on or off.
Be able to fire a gun as a while descending in a parachute. You're just a sitting duck, otherwise.
Fixes
For multi-player games when joining the server, increase the height of the <unassigned> player lists. It's a pain when joining a large game to have to scroll up and down the list to find an available slot. Also make it so that if you do have to scroll through the list, that the scroll-bar stays put. I hate when I have to scroll through the names, find an unassigned spot, only to click off the list and have it scroll back to the top. Perhaps it could be made so that the list will scroll down as necessary.
Fix collision-detection in general. I don't like falling through a window or fence, ect, because I got too close. There are other inconsistencies as well.
Some of the physics are kind of weird when you see a vehicle bouncing up and down forever until the game ends.
I believe tank speed on hills was addressed, but if not that's another suggestion. On especially steep terrain, they often slow to a crawl and in some cases will roll backwards if you didn't have enough momentum to start the climb.
Make a switch for server admins that can be turned on or off to prevent the opposing side from coming within a certain radius of your base. I know this is a strategy in some cases, but then again a lot of multi-player games have been ruined by the opposing teams destroying every vehicle in your base and of course spawn-camping.
Get rid of the damn seagull in games with spawn limits. Allow dead players to scroll through the remaining players' cameras.