Close to a sim, minus several substantial key flaws.
Forza Motorsport is a game -- Do you drive a car with a joypad? No. Then how is Forza a simulation? Entertaining, absolutely. It's a game.
Gran Tourismo is a game.
Race Driver Grid is a game.
Need For Speed Shift is a game.
The people at EA have again largely blown a great opportunity to create a captivating game by failing in the part of producing that, in my opinion, they have never succeeded in -- Fit and finish. The graphics are great, and moreover they are beautiful but still light enough that with a bit of tweaking, systems that are a few years old can still run high settings with good FPS.
The tracks are amazingly reproduced, however my only knock is on their representation of Laguna Seca, the dogleg coming out of the downhill esses has an incorrect apex -- The apex is a bit late in their version of it.
The AI is mediocre at lower levels, downright crazy at upper levels. It makes the career mode a bit tough to finish.
As a GAME, NFS Shift is worth a try. I use the NFS series as a strict break from realism as racing nothing but simulations after a while can give you a headache. The NFS series has long been my oasis to regain my thoughts when struggling with a simulation, and NFS Shift is no exception. I do not play it for a realistic experience.
The reason for the 5.5 is simple -- The oddities and inconsistencies of Shift make it, at times, unbearable to play. It can become so aggravating that it will make you want to toss your PC out the window, and if it were because the AI is so realistically tough, that would recieve bonus props from me. But no, it is because of the myriad of issues this game suffers from.
I sincerely hope that very soon EA will finally give up their pursuit of joining the simulation party of PC content. They have shown for almost a decade that they can't do it -- In fact, the only games they've ever produced that were even remotely realistic were F1 Challenge 99-02 and Sports Car GT, which to this day still has some of the best AI and roll-over physics I've ever seen.