Below is my impressions of it from a comment above, after two hours, I'm on a break from my latest session and maybe another hour after a cold boot of my PRO and man, I really undersold this. It looks, sooooo much better and runs so much better to but the points below still stand but just a lot undersold on how the visuals looks on screen, the texture pop in and the driving.
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My experience with 1.04 on PS4 after two hours, for anyone hesitant, updated from 1.02 which I played from launch to 13 hours.
Runs better and it's as stable again as the first 5 hours. I can drive my car now even at high speeds and while the world will still fall apart it doesn't require a restart to get it back, things load back in the instant I hit the breaks. I can fast travel now without fear of it freeing. I've had a few, maybe a handful of slight frame hitches which is about the same as before but the difference being they don't last or get worse, they iron out. Basically, I don't need to restart the console, even after an instense fire fight.
It looks better: Not a mircle patch but things and textures load much faster and things look sharper, there is less of that kind of Dreams fluffiness around the edges of textures and definitely a lot less on the textures themselve, the road is the biggest difference, it doesn't look flat anymore, has way more texture to it and reflects I might be mistaken or didn't notice them before put the puddles are reflecting at night now, almost sure that wasn't the case I remember thinking the rain is only for show. I also have my console turned back onto 2160p in the PRO settings and that's huge cause it when things do load in, your walking or just panning the camera to actively look at the scenery and it's all solid and smooth the ceiling for the resolution is noticably higher but it still make little difference if you're running, in a fight or other intensities like driving the car, the latter being the only case you'll notice it cause you're actually looking at the scenery.
The fans: They're more consistent and smooth and they don't reach the roaring chainsaw levels even in intense situations. About the same as the "fix" of changing the PRO settings to 1080p.
Crowds: They're's less people now and I think less traffic but I can't be sure of the later.
Haven't noticed much else but this is just enough, enough to make the game playable again. Having it stable is not something i should be praising or excited about but I am. The game is still buggy and visually all over the place when doing things but this is a start and a gigantic leap over the OG PS4.
One thing I'd like to see is an auto drive mode like from watch dogs, with differing levels of speed. I'd much prefer to get around like that and I'm sure they could make things more stable with a mode like that, at the very least I wouldn't have to be panning the camera all around and seeing the janky world.