Fashion Show is a mega mall with almost all the brand stores you can think of. It's a great place to get a lot of shopping out of the way and you can spend the whole day there.
But like a regular mall the sales are not really that big of a sale (except for Macys, who are always on sale with discount on top). If you like to look and browse for deals and steals, I would go over to the outlets.
This place is good for out of towners who like to shop and really good for international travelers because the prices are cheaper than where they live.