For those considering a purchase who are big into live sports in the USA I think it's important to call out that the 900E is a major downgrade from a 1080p panel when it comes to broadcast content that is 720p. Whether the upscaling is handled by the 900E or by your DVR, it seems there simply are too many pixels for the TV to recreate and the blocking, smearing, screen-dooring, etc. are more visible than you're used to.
In the US, that means networks like FOX, ABC, Big 10, FS1, MLB, ESPN, ESPN2, Disney Channel, National Geographic, and others carried by your local cable or satellite provider are going to look worse on your brand new Sony 4K TV than they did on a comparable 1080p TV.
The 1080i broadcasts will look stellar, they'll be a major step forward in clarity, brightness, and color. But if you are a fan of NFL football or MLB baseball, be prepared that about half the games you'll watch are going to look a little crappy.