If you're trying to sell your used duds take heed! This place is very picky. Basically, they want items that you are probably still wearing! This, however, works great if you're a buyer!
If you've recently lost/gained weight or have access to samples of current trends then this place would be okay to sell. Still, you don't get much more than if you sold your things at a yard sale, actually, you'd probably make more that way, but this way you avoid the hassle and inconvenience of hosting a sale.
Also, the place is not that big and the aisles get crowded. This is not unusual for SF, though.
BUT, if you're looking for the classic downtown-sf-financial district-biz-casual-but-trendy-on-the-weekends-girl-on-a-budget-wardrobe then girlfriends this is your place.
Sine qua non?
Recommended for buyers, but only a select group of sellers.