Whether it be Christmas, birthdays, or any other celebration, gift cards are always labelled a terrible gift (usually along with socks).
I can, to a certain extent, see why. Yes, they seem unoriginal and perhaps like you barely know the person. Furthermore, they also tell you exactly how much that person has spent on you, either making you feel unappreciated or perhaps like they've given you a lot more than what you spent on them.
However, I personally feel like they are wonderful gifts! A friend of mine gave me a £10 Waterstones one for Christmas, saying that she didn't potentially want to get me the wrong book, and I'm okay with that. As long as you get someone a gift card for something they enjoy (it would have been stupid to get me one for a clothes shop for example), it means that you avoid any chance of buying something dreadful. As I read so much, it would have been really difficult to get me a book that I haven't already read, without risking it being something I wouldn't like. This way, I can pop along to Waterstones after Christmas and buy anything that takes my fancy - it also avoids the stress of buying presents for the giver!
Of course, family or a significant other should probably warrant a little more than a gift card, but for friends and colleagues, I do believe that gift cards are a fantastic idea and require a bit more thought than just slipping a £10 note inside their Christmas card.
All I need to do now is to decide which books to spend it on!