Looking forward to the cloud service mainly, every time an xbox died I lost my saves, then with the elite-s they ditched memory cards to f**k you up etc... It's a pain when you loose saves, especially with forza 3 when they would only send the special edition cars just the once!
But there's somewhat off a negative to the cloud save service depending how it works, as it may make achievements a pain to get, as you could quickly do option a - get achievement, reset and do option b and get an achievement. Like with Fable where you got 3 endings and each one was an achievement, or in Dragon Age where the entire game like Fable was based on two options.
Quite like the FB integration as that has been on the PS3 for ages regarding achievements.
Is there a browser built in and an iplayer as an extra content is a bit vague, iPlayer would be awesome which is what I loved about the ps3!