Prior to update 1.03, the game was running just fine for me.
Same here. I got to Novigrad (in the process of finding out where Dandelion was) before 1.03, so I'd been through the swamps and everything (done all the story stuff in Velen), and the only time I would experience any problems at all is when I was in the middle of a swampy area, in the rain, with the wind blowing while fighting a group of drowners, and only then, it was a couple frame drops. It was running beautifully, and it looked gorgeous. I thought to myself "I was worried the PS4 couldn't handle it, but CD Projekt really pulled through."
The only bug I experience from day one until 1.03 was at the very beginning in White Orchard, I was going to the nobleman for the first time (through that marsh with the pack of wolves) and all of a sudden the water popped in this strange black outline or something around its borders (similar to how usable things has a yellow glow around them in Witcher sense, but black and all the time). A save and reload fixed it and it never happened again.
After 1.03, the blacksmiths stopped appearing in Novigrad. I had to meditate in front of their shops to get them to spawn (I've since completed Swords and Dumplings, and Hattori doesn't have that problem). Now, I'm getting pop-ins where I wasn't (usually NPCs, but I've seen a couple trees and grass patches), the fur some people wear looks like plastic, and everything looks somewhat lifeless in a way it didn't before. Also, anyone carrying a box now has a strange reversed walking animation, while they're moving forward, which was funny when I first saw it, thinking it was that one guy, but then I noticed it was everyone, and now I'm a bit annoyed
I thought I had been playing too much, and was starting to notice flaws just by looking at it too long, but I really think it ran best when it launched.
I'm right at the end of the story, so I'm going to finish my playthrough. But I really want to play through again to see where alternate story threads go. I'll wait a couple months before then, and hopefully all this will be remedied.