When you walk in the door, you'll instantly know that this place is run by fans for fans. (It should be noted that staff has hygiene and social skills.)
They will help you find what you want and will suggest other things you will probably like as well. They have great coupons in their e-newsletters, and ASU students are regularly treated to discounts. When I purchase a significant number of comics, they'll often throw in free bags and boards. There's a small fridge of cheap cold soda and other drinks, which is refreshing during hotter months.
The main drawback is parking. Both the few official spots and the street fill up during busy times. If you're accustomed to parking in the Mill Ave area, you're already aware of this.