Here's my experience with AMEX Serve: I have never had a problem with them and I use Dollar General. I have done this over and over again. I have used multiple different, new cards and I have reloaded multiple times as well(for free, I might add).
The only things that I would advise that you do is 1. write down all of your info on your cards; don't take this for granted; I did not and lost one; now, I do not know if my money is still on my card IF I FOUND IT(lost it at home, so I looked and looked for it, could not find it, and there is an almost $5 fee per month). If you had your info, then you could just use that to make online purchases and the like. This also would help you know how much is on your card as well.
2. You should also REGISTER to ensure that you can get a replacement for your lost card if you are the type that uses your card to pay bills, at restaurants, for direct deposit, at grocery stores, etc. The second one does not apply to me, because I typically load my card up and go make purchases online quickly(since I live in a remote area and this helps me).
Still, make sure that you at least copy your complete card info, in case you ever need it. On a site(LIKE AMAZON OR PAYPAL) where your card is saved, they will only give you the last 4 digits and no security code.
My experience has been great from AMEX SERVE'S end, though. I have not had to call anybody about issues. They have made finding out account balance really announcing now, when it used to be very easy!
Product or Service Mentioned: American Express Serve Prepaid Card.
Reason of review: Problems with payment.