The balance is nowhere to be found on the card, but on a receipt you get with the card. Both can get lost, and at the very least they'll get separated. Worse, this balance expires if the card remains unused for a period of anywhere between 12 and 24 months.
Retailers claim that gift cards are preferable to paper vouchers that don't expire, suggesting it avoids situations where people try to buy goods using years-old, moth-eaten vouchers and risk being refused. But really, it's a way for them to use terms and conditions to steal your money; take too long to decide what to spend your virtual balance on, and said balance gets nullified.
Virgin Megastores, as was, tried to stick these bullshit terms and conditions on their gift vouchers, before so many people complained that they were forced to remove the 12-month expiry, which of course returned when they started their gift card scheme. Since Virgin sold its megastores to lowercase zavvi, Virgin gift cards are still valid; only problem is zavvi has now closed the only store that was close to me.
HMV Group, meanwhile, has taken this gift card scheme to new heights of insanity. Time was, HMV (music store) gift vouchers were valid in Waterstone's booksellers, and Waterstone's vouchers could be used in HMV, as both chains are owned by the same company. Since HMV and Waterstone's eagerly switched to selling gift cards, this freedom of choice has disappeared. HMV gift cards are only valid toward HMV purchases, and Waterstone's gift cards can only be redeemed in Waterstone's.
After spending £49 of my £50 in M&S gift vouchers this morning, I'm left with a £1 M&S gift card.
I am so opposed to gift cards now that I will send back any I receive. I would encourage others to do the same.