Riffle shuffling in your hands is a bit more difficult than using the table, and it's more likely that the people you play cards with won't know how to do it themselves. Once learned, you can quickly end with a flashy bridge finish for additional effect.  This method is not used in casinos, since other players can often see the cards during the shuffle. Like any riffle shuffle, this does bend the cards, and can wear them out faster than other shuffles.

Summary:
Use this shuffle to impress.