Yep. And you're still getting any special merchant-specific rewards the card company might offer you. I just reloaded my Starbucks card using my Amex, and Amex had a promo that offered a 10% credit back on Starbucks purchases, up to $5.

So I threw $50 on my card, I get 10% off the coffee, and earn back a bit on the Starbucks reward points.