I love to receive gift cards as presents because it will often allow me to do something I normally wouldn't do otherwise, i.e. go out to dinner, to the movies, buy some new clothes, etc.
As for giving, I always get an enthusiastic response when I give them as gifts. This year we got MIL a g.c. to Joanne Fabric (we got her one for her birthday last month and she let us know how much she liked it and wouldn't mind getting another!) and FIL a gift card for I-tunes, on the suggestion of MIL. He went out of his way to let us know how much he appreciated it. So, carefully chosen, I think they can be wonderful gifts.
I agree with a pp (I think it was Princess Perky) that if I receive money, I will use it for a regular expense. But if I get a gift card...well, then I just HAVE to spend it on myself
