Yea I drive in light overcast conditions myself pretty often. I like the change in lighting when some clouds cast shadows over the track. At indy, I drove on the back straight in sunny conditions while just half a lap later the sun and dark shadows were gone... So dynamic, so real-life, so immersive
If you like the way it works, then I guess you haven't seen a proper Sun occlusion, yet

Personally I don't like how it's done. If some cloud casts shadow over part of the track, I'd like to see it this way, not have lighting settings change for entire world simultaneously.
There's a difference between:
- driving from dark side of the track to the bright one
- driving on a track that goes from dark to bright everywhere at once
I find current effect very misleading - may trick you into believing it's going to rain. There's really no way of telling the difference. Yesterday I've spent a great deal of time driving Nissan at Portugal at different conditions and I've found visual representation of weather very misleading. There's just no way I could refer to what graphics engine was doing.
First indication of rain for me was dense water spray suddenly appearing in my rear mirror - and I was at the hairpin when that happened (!). "Is it raining?" - I thought. Had to look closely to notice raindrops. Next indication was decreased grip. Barely visible reflections on the road was the final indication of rain - long after grip levels dropped. I really needed to stop the car and look around to notice reflections.. The visibility was still excellent. I could see a bit of mist, but only at some distance.
How it should be? First - we need to see the rain coming - rain clouds getting closer or building up above. Next - we should see visibility dropping where rain is and raindrops if we are close enough. Third - we should see road getting wet - by noticing higher reflectivity (especially sky reflection should be obvious). And this is when grip levels should start to drop and water spray appear ( but it should not just kick-in like V-Tec

).
Considering that grip levels dropped before I could finish a lap... Well - let's just say I will not participate in leagues that use variable weather in rF2 at it's current form as race result could be determined where rain caught you (beginning or end of lap).
Right now it starts to rain out of nowhere and real road gets wet quickly, so you may not make it to the pits on your slicks. Having no other indication of incoming rain apart from change in lighting condition and clouds, you're pretty much left with no information. Especially that Sun occlusion effect can look exactly the same as beginning of rain.
While I don't expect anyone to make a fancy, life-like looking sky and clouds for me or some nice raindrops on cars, I do expect visual cues to carry some basic information. While I can sit in any of ISI's cars and instantly understand it's physics, I can't make anything out of ISI's environmental effects.
By the way - thanks everyone for posting IMS and DW12 videos - at least I got to have a glimpse while still being at work

But now I'm off to try it out myself

Cheers.