Played a lot over the weekend so here's my input so far (PS4, pad, pro handling, all assists off etc):
-karts: made the mistake and started the career with a kart championship, after an hour or so I contemplated about breaking the disc in half, never had such a frustrating experience in a sim before. Took a while to get used to, managed to master them and won several championships. But I would never ever drive them again, they are simply not fun to drive.
-pad settings out of the box: UTTER AND COMPLETE SHIT, I can't figure out how this game shipped with controls settings not calibrated for the DS4, it's like it was not even tested. Some race cars are simply un-driveable until you tweak the pad controls.
-steering lock: the moment you try to take a chicane (fast left-right movement on the pad) the game only recognizes one input and fully locks the steering wheel in that direction making the car lose control and spin out. It is apparently fixed by setting deadzone to 0 (I still get this behaviour in some cars at reduced extent) but still massive oversight at launch.
-the career mode: absolutely no incentive to advance, no rewards, no xp, no unlocks. Finished your race? Good job here's another one aaand another one aaaand ano... :/
-unpolished, rushed game: lots of bugs, from cars getting out the pits straight into the wall to coming into the pit lane straight into the wall, once had my car stuck in front of the pits because it kept hitting a CONE made of cement apparently right and kept backing up and forward into it again and again. Graphical quirks here and there, some slight tearing, cars have no lights in the mirror and things dissapear so fast in it, slight stuttering once in a while (very annoying when mid cornering), LOD changes just ahead of your car, people I play online losing calibration on their wheels at race start, sound cuts and so on.
-weather: an obviously strong personal opinion (and one I had since the first videos of PCars weather emerged) so I won't beat the drum too much on it but I don't find the weather graphics as being nice (ugly wet road textures, ugly rain droplets on screen/windshield, no rain drops accumulation), there is another recent game that does it much much better.
-unintuitive, cumbersome menu UI: you expect a 2015 game to be better at this also a very poor choice for a text font
+race cars
+race cars
+race cars
+engine music
+tracks
+online
On the plus side this is what makes the game a solid buy for me, although I honestly expected a lot more and rightfully regreted the purchase the first hours or so (fuckin stupid karts). Some beautifully crafted machines, a nice selection of race tracks and a pretty solid online experience. Whether it's GT3 class, formula rookie, LMP or vintage race cars this is where the game shines. You can see the dedication and work that was put into developing these cars (as opposed to road cars that drive like shit), the models, the sound they make, the way they handle on track just pure bliss. The moment will come, whether you're roaring around NurbGP in a Z4 GT3 with friends or just cruising alone at Oulton in a 1967 GT40 at sundown, when it will all make sense.
If you're on a fence about PCars I'd say wait a few months till most of the problems get sorted out. If you're a petrol simhead then this game is just for you right now. It is a sim but not a fully hardcore one, I would say on par with GT/Forza with a lot more settings to tweak here and there. If Polyphony could learn and adapt to some of the pluses this game has and build on those what an amazing GT game will turn out to be.