The biggest oddities for me are that it’s not going to be backwards compatible with XBox 360 games, and the DRM will prevent used games (as the game serial # is now tied to your account).
The latter I see as a natural evolution to the similar system as Apple has for tying iOS apps to your user account. It makes sense, but the side effect of killing the used game market (if it’s true) is a bad one, especially when you’re talking about $60 games instead of $1.99 apps.
The former I honestly don’t believe it’s true. MS is the king of backwards compatibility, and making it so that a hardcore games (no doubt considerable) library of XBox360 games is useless (unless they now have two XBoxes hooked up at all times) just seems ridiculous. I know the new XBox One is more than just gaming, but really, I don’t believe that’ll happen. Guess we’ll see on launch day (no idea other than “later this year”) when you can buy it (no idea for how much).