Its not a 'huge' difference as a standard PS4 looks good on a 4K screen, seeing 1080p upscales cleanly. The problem is games are not really using higher resolution texture quality, just the same assets rendered at higher pixel count for the most part. The games that make good use of Pro's power look nice and clean on a 4K TV.
But if you are buying a PS4 for the first time, trading up or selling towards one, i don't think the price is exhorbitant and you do get a larger hard drive.
I was able to get a deal on mine BNiB for $300 on a classifieds app. Got the better end negotiating with a scalper a month after launch, guess he was hoping for an availability drought on limited funds and ended up pinched for cash. For that price i'm not complaining, its a great console and much quieter than my launch PS4.
PC I i7 3770K @4.5Ghz I 16GB 2400Mhz I GTX 980Ti FTW
Consoles I PS4 Pro I Xbox One S 2TB I Wii U I Xbox 360 S
