Answered by Mukesh
The recipient sees the value on the card, because they need to know how much they have to spend. What they do not need to see is your payment, and the gift is presented as a card of a certain value rather than as a receipt of your transaction.
If you add a personal message, that is what carries the warmth of the gift, and it is entirely up to you what to say. Many people like that a gift card makes the amount clear while still feeling thoughtful, since the recipient gets to choose exactly what they want.
If you would prefer to keep things low key, you can simply let the card speak for itself. Either way, the focus lands on the brand and the value you have given, which is usually exactly what a good gift is meant to do.