A lot of ambient sounds are still missing. There's nearly no audio of items falling onto your tank, especially very heavy items that would be impossible to notice, even for a deaf person.
There's also no audio of dirt falling onto your tank when a shell lands nearby. Things like this turn an okay ambiance to an amazing and in-depth one.
Also, personally I'd like to have a little bit more control over the specific isolated audio channels. Just having everything about the tank fall under "tank" instead of treads/ground and engine separately, while collisions and gun shots fall under "effects" doesn't allow for a good feel for those of us who are more audio reliant.