Aeropostale has really cute, stylish, mainstream clothes at reasonable prices. I'm a student and I shop there a lot for my wardrobe basics. They are very affordable - much better prices than American Eagle, Aeropostale, or Hollister.
Their t-shirts and sweatshirts are really cute. They come in bright, pretty colors and have cute logos, graphics, and sayings. Everything is durable and long-lasting and fits well.
The only thing I don't like about Aeropostale is that their clothes can get a little boring if you shop there all the time. Their clothes don't seem to change much from year to year or season...