Need for Speed: Shift is easily the best Need for Speed game in recent memory and is one of the year's best racing games. As mentioned, even if it's deeper than an arcade racer, it's not a details-obsessed sim like Forza or Gran Turismo. However, it's more fun and approachable for a larger number of people.
There's always something to strive toward in Shift beyond finishing first, and the actual driving is rewarding thanks to the amazing cockpit camera and spectacular controls. If you're a racing game fan, go ahead and pick up Need for Speed: Shift. It brings back a lot of the fun that has been missing from sim-oriented racers for a while.