IMO the upgrade to the PRO just isn't worth it.
I think if you've seen modern PC graphics, it might not be worth it, but if you've only played on consoles for the last 5+ years, it's a different story.
It was never going to beat a PC - but I think what it achieves is pretty great for the money. For the cost, I wasn't expecting miracles. Yes, I got a 4K TV too - which cost the most amount of money I've ever spent on technology - but that works for more than just games, obviously, and I believe getting a decent 4K PC monitor (especially with HDR) is a bit of a nightmare.
I'm glad I've got the Pro - I went back to PES on the standard PS4 at a friend's house recently and, despite not thinking there's much difference on the Pro day-to-day, I was pretty shocked at how much worse the faces looked. I mean, they weren't
terrible, but after being spoilt with the Pro at home, I couldn't believe it. I didn't think I'd even notice, but I was immediately struck by how much blurrier they looked.
My only problem with it is that the fans are absolutely bananas, I genuinely think it's a bit of a disgrace. Even in the days of the 360 kicking out some serious heat/noise, I could hear the TV over it. Now, I have to put headphones on, or I'd get complaints from the neighbours for turning up the sound so loud, seriously. And it's not like it's a rare occurrence - on PES, it starts when you're on the pre-match setup screen. Not exactly the most intense task...