For me, there's no humbug about it whatsoever. I'm not grumpier around Xmas than I am at any other time of the year - I just object to being told that I ought to be happier...
I don't send cards, though I will if someone sends me one so as not to appear rude.
I can understand how much children love it, of course, as I did myself when I was a child. However, looking back, that was entirely down to getting presents - nothing else.
I can understand that it might mean something to Christians, though these days you'd be hard pushed to find one who actually believed that Jesus was really born on 25 December...
And I can understand that some families use it as an excuse to get together. That's great, of course, but doesn't apply to me.