I am a loyal forever 21 shopper, mostly because I am a low budget shopper. I am able to find things there that are different, or interesting, that I get alot of compliments on.
I agree with others that the store can be overwhelming, crowded and disorganized, but I really think that is a function of the store layout and the management/employees there. I live near 3 of them, and one in particular is very large, yet not crowded by merchanise, and always see many employees organizing.
I also agree that its a great place to find accessories. My favorite Forever21 has a huge room of just accessories. I especially like to buy cocktail rings and large earings there. They also carry hats, bracelets, wallets, and fabulous clutches.