Some fast first impressions:
The actual FPS is a bit lower, but it feels like it is a lot higher
Flying at high settings below Tower bridge is around 50 fps but it's completely stutter free... It has been like that before but it just feels better now. The effect is more obvious in the attack bombers over London mission. Stays at 55-60 fps all the time even when blasting away at short range with debris flying (and hits being shown). You can still empty all eight guns at a bomber spraying both engines and fuselage without downing them though
The prop effect now feels as i should - a slight haze and when changing rpm some "disturbances" in the haze are seen etc. Before on my 120Hz monitor I saw way too many blades and "flickering" that was REALLY annoying.
They have done something with the "clarity" of things... The Hurricane cockpit is extremely "sharp" looking now... And in my glass half full world everything looks sharper in the landscape etc...
The sounds feel even better - but they where awesome before too... Can put the finger on it but the Merlin sounds even better? No other game is even close as we all know...
I can still down a He-111 in my Spit by cutting his wings with mine without damage to my trusty titanium Spit
It seems harder to overheat the Spit 1 and Hurricane at least? And the Spit 1 seemed to accelerate better?
Summary after 30 minutes of stick time - it really feels like a solid patch! No real bugs accept that collision detection problem with easily cutting the wing of one of those bombers withstood all my bullets hitting it with just two gunners killed and some smoke from one engine (and half lowered landing gear that looks so nice).
EDIT: And almost forgot that the German gunners seem to hit me less often? Or is it that I have flow RoF lately where you get oil smear over you goggles just by looking at a rear seat gunner?