1) Stripes of water in land, land in water, variable severity, no obvious cause.
2) Disappearing sound in multiplayer yes, but lack of external sound as in Black Death track is ludicrous.
3) Propellers disappear behind clouds, grass pokes through your wing and waves about in the breeze.
4) If a line of vehicles passes behind your aircraft on the ground, a line of white dots parades across your aircraft.
5) Buildings not only appear suddenly, but are a shade of dull brown until detail kicks in, grey would be better.
6) AI behaviour, particularly dogfighting bombers. We finally got rid of aerobatic bombers in IL2, now they're back.
7) Flickering clouds, cloud shadows and ground shadows
This isn't a bug, but the bloke sitting next to you in the Ju88 looks like something out of Resident Evil. Is he already dead when you take off?
9) The ceiling capability of all aircraft needs a serious look
10) Mixture settings seem to confuse rich and lean between aircraft
That'll do for starters.
