I'd agree with the list, but I'd make #1 ACHIEVEMENTS!!
The concept of Achievements is huge, and really overlooked by non-360 players. It adds a lot of replay value to a game, gets you to perhaps explore games in new ways, and gives you the ability to compare how you are doing to a friend. Really adds a lot to the sense of community.
Note on the live file size limit: The file size limit only applies to Arcade titles. HD movies can be downloaded and they are often 5-6 GIG in size. The 360 also lets you start watching a movie download before it is finished. i.e. I just watched Transformers in HD (6 gig), and it was able to start playing within 5 minutes of clicking download. (The PS3 may do this too, I'm not sure)
See but I'm not a fan of "needless" achievments. Personally I could give a rat's ass about the size of my E-penis, if they make them actually mean something I'm all for it :D, unlockables are great, extra content, making of scenes, cheat codes etc etc. I mean I do think it's cool and all that you could go for some extra "objectives", but it's kinda like those flags in Assassins creed... you get them all, it tells you that you've gotten them all, and... well... congrats!... It's just empty :/ I'm not a big fan of achievements and I'm not sure but if they have the option to turn off the blip that shows up on your screen every time I'd personally choose to do away with it :x Unlockabales for the win :P
As for the video's, yes, you can download and stream it. However all we have are some developer diary's and stuff >_>; we don't have movies xD because SONY isn't on the ball with one area I feel they really should be :P
Thank you for the clarity on file size :P Why only for games? xD That doesn't make much sense to me LOL
From 0 to KICKASS in .stupid seconds.