The most dramatic difference I've seen in quality, was with FF14 ARR. The game totally coked the PS3 in so many ways. Compared to the PC version the PS3 version was terrible. It was 720p (rendering seemed sub 720) with all kinds of effects turned way way down, lighting engine and shadows obviously turned way down, textures seemed low quality, and it just generally looked terrible compared to the PC version, even if I put the PC version on 720p resoultion with the Laptop Performance preset, the difference was HUGE. And that's before the dealbreaker. The PS3's RAM wasn't sufficient to load all the objects on screen, so when a lot of people were in the same area, things would disappear. Important things, like friggin enemies!! And the CPU was just getting crushed, bringing the FPS into slide show range in these scenarios.
My experience was that the PS3 was actually terrible for a lot of game types. MMOs being the most extreme example (not enough RAM, not enough CPU power), but certainly also open world games (like GTA and Assassin's Creed). It always bothered me in something like AC2, to walk through a city, and turn a corner into a plaza or something, and notice the FPS clearly drop below 20. I mean, I can tolerate a solid 30 FPS, but as a PC gamer, when it gets into the 20s, it's just not good enough.
And making the problem worse, it seems devs really really pushed the Xbox360 and PS3 hardware too hard late in the lifecycle. Narrow FOV, fog in the distance, low res textures, and so on, in a game that's trying to do way way way too much for the hardware, and still crushing things into the teens, on a frequent basis.
Infuriating. Pretty much why I played on the PC more than anything else last gen.
Anyway, for right now, the PS4 plays things similarly to a high end PC.
With the FF14 ARR example, the game runs smoothly at what's similar to High settings on the PC, at 1080P. No pop in, no crippling FPS dips, almost identical effects quality as PC. Funny enough, not only does it look graphically as good as the PC version, but mouse and keyboard settings weren't cut out of the port, so you could actually play it like the PC version, if you wanted to with mouse style hotbars and WSAD keyboard movement and such. A few graphics options are available even, in locking the FPS to 30 if you want, or going to 720p (which can help with certain displays).
- Really, the main difference between the PS4 and PC versions, are in communication methods. On the PS4 you can conveniently invite PS4 friend-listed people to a party chat, and on the PC you're more easily able to use Vent or something.
My experience with Warframe was similar. Seemed like a pretty direct PC port, had some graphics options in there (can turn off DOF and such if I wanted), and ran really similar to on the PC. Looked really nice....
AC Black Flag ran really nice. Locked to 30FPS, but never dipped in FPS, even in cities, 1080P resolution, almost no pop in.
For me it's not that it's a world of new possibilities, its more that the PS4 is finally running the types of games released last gen, in a capable way.