Pros
Excellent product and brand. You can treat your customers with respect and go to bed at night secure in the knowledge that you've sold them a great product at a good price. Carmax takes great care of its customers. While no company is perfect Carmax is always striving to improve. The Carmax sales process is very customer focused. It's truly a great place to buy a car.
Cons
The pay per unit sold is below average. Carmax management is very top down and and centrally managed. This means that at times policies are developed and implemented by people that have literally never worked in a store. The field management has too little autonomy. And, at least in my store, management is disinclined to listen to the front line employee including the sales associates.