We canceled our cable subscription about a year ago, and while I was OK with it my wife hated not having certain live TV channels. We'd tried Sling, but it was hit-and-miss on the stuff we wanted. Some channels, like BTN, aren't available at all on Sling. DirecTV is only a little more and actually covers the live programming we want.
Make no mistake, the launch was rough. I don't think they allocated enough hardware or bandwidth to handle their initial demand, so streaming cut out constantly. It's finally getting to be pretty solid, though, and I'd much rather pay Sling a few bucks than have anything to do with Comcast.