My daughter bought me and my wife one for our 40th wedding anniversary 18 months ago - I guess it was a pretty new thing when we got it and they have probably improved now in terms of features and price. Mine is a Philips and quite simply I think it's BRILLIANT!
My particular model doesn't accept xD cards - which is what my camera uses - but I can wire it up direct to my camera (all cables were included). I also download photos from my computer onto a 1.0GB SD card which the DPF reads perfectly happily.
I am delighted with my Digital Photo Frame and I think it is a wonderful present to give somebody.
Do get one, and make your mother's Christmas.