The big issue with the Xbox One originally, before it launched, was that you weren't going to be able to play used games on it, and that it was going to have to authenticate all of your games through an online connection once every 24 hours. They ended up scrapping both of those ideas because of the backlash they received.
The backward compatibility they're working in actually sounds like it could be decent. Yes, it will have to download games after you put the disc in rather than just playing off the disc, but that's more because the Xbox One doesn't play any games directly off the disc (most if not all Xbox One games do a full install and just use the disc to authenticate). It sounds like the main hurdle will be whether or not publishers agree to have their games be included. Digital games, you'd have to download anyway.
The upside to this is obviously that, for compatible games, you won't have to pay anything if you already own it.