Since the 4E release, I've made my own cards for my group. I designed them to be good looking, with the flavor text, and the mechanical details on there as well at the bottom of all of them as needed, Attack, Damage, Ability Modifier. I print them up on high quality paper, slip them into a protective card sleeve, and then they attach the equivalent of price stickers to the boxes for the Attack, and so on, and then write their numbers in there. When it gets to be to erased looking, slap a new one on and away we go.
And I print out the cards as needed. And I can easily go in and adjust all the powers with future erratta as necessary.
I built base templates, and just copy and paste the good bits in and away we go. It takes me about 2-3 hours to do every single power and the paragon paths for a class, or when I'm working I can finish an entire class in a night. As it is, I've only got 4 more left to do, and then I await the next book, Arcane Powers, and so on.
I also make cards for each of the published dragon magazines, and just throw them right on in there. My players, find my cards to be so useful, and we've all got DDI but they prefer to have the cards in front of them. But they prefer my cards, not the way to late to the dance, look like crap cards. (Sorry designers of the WotC cards, they just look like the most basic uninspired rush job that one could well.. rush out.)
So no, we don't use them. Mine are better, and more easily customizable.