I once used Bit-X prepaid card to load Bitcoins to it. Eventually, I lost money because each time I used this card to pay for something, the exchange rate was unpredictable and not the best one.
Therefore, my scheme is as follows. I have a Bitcoin wallet where I store Bitcoins. If I want money on my ordinary card, I convert Bitcoins to USD at the rate that I see and can more or less choose, and withdraw the money (USD) to the card. Since CEX.IO introduced the feature of card withdrawals, I am using it more and more. I even ordered a VISA card at my bank, cause the withdrawal fee for Visas on CEX is $3.80 only.
As said, I am not dealing with prepaid cards anymore, because it is not as transparent as I'd like it to be