Well, about physics in pCARS I have to say that there is a lot work to do yet. There is a problem with the mass of the cars, they just don´t feel and look natural...any experienced sim racer can tell you that. (many will disagree because they are blinded by its graphics and probably never played rFactor, rFactor 2, nKP, GSC 2012/2013, or Assetto Corsa)
I have pCARS since October 2011 when all started, the graphics are good yet there are things I personally don´t like but can be turned off on PC of course. (like the lens flares, or motion blur which I hate so much)
Sometimes even by the game looking great, there are some details that can be better, like the asphalt textures and such which sometimes looks way saturated and the colour palette could be way better than it is compared to GT5/6 and now Assetto Corsa which in a more simplistic way is looking better than pCARS in my opinion. (I also have Assetto Corsa, physics are more realistic, cars feel like they have mass, you can see the weight transfer working with the suspensions and all, yet they have to improve the FFB and some things...but they are way ahead of what pCARS has to offer at the moment)
pCARS is not a NFS Shift though, but if the "mass" problem I am referring is a graphics engine issue, I doubt that they can change it...maybe compensate somehow, but since I play rFactor 2 (which is playing in other league when it comes to simulation despite its graphics which sometimes can look really good too), GSC and AC,...pCARS in the simulation aspect is way behind them as of now...I just can´t enjoy the driving...it doesn´t feel natural in the wheel and in the visuals. (best way to find out is by playing it)
AI is good, you can actually race with the AI, they can beat you and fight with you. You can have fun with it.
Car list is getting better because we are the ones choosing which cars the game will include in it...I´m not sure at the moment how many cars will be at the end though. The variety is actually pretty good, some, open wheelers from Skip barber, F3000 to F1´s, LMP, DTM, GT, Street/road, Supercars, some licences like Mercedes Benz, McLaren and some more.
It has some positive things...but as a hardcore simulator fan, at the moment is not making out for me in that aspect. Is not bad and is way to early to say the final word about it. Game is updating every day, sometimes they make a car feel better, sometimes they ruin a car, then they fix it...etc.
Is too early to give a final opinion. Career mode is under construction, it has online and it works. Leaderboards...etc.
Some pics of mine at Willow Springs with a Pagani Huayra (GT6 version looks way better):