just to take a stab at what all i think is going on here...
left to right, top to bottom:
-icon to quickly get to the PS Store via triangle button like when you're in the current store. (dedicated home screen tile for it may or may not exist)
-the area where system alerts and messages will show while on the home screen. in this case the user just logged in, and it's obviously morning time.
-icon to quickly get to friends list. again, probably by hitting triangle like in the store. (just guessing at this point but it will probably be much easier)
-indicator as to who is currently logged in.
-icon to quickly get to system settings.
-clock that will most likely be broken and won't get fixed for a long time.
-What's New tile.
-Watch_Dogs is either installed or in the disc slot.
-Drive Club, Infamous SS, Destiny, Knack, Final Fantasy, etc. showing all the games the user either has installed, or has been played recently by disc.
since we can see X is select and O is back, then we know you highlight tiles and icons with the D pad and hit X to select them like we're all used to with XMB. and the more you look at the horizontal row of tiles, the more it sort of resembles the XMB sans the columns under each item. and judging by the other screens, it seems that when you select an item that has more info to show, such as What's New, it will allow you to scroll the content downward. hitting O should quickly bring you back up to the main tile under the category you're currently in.
i like this better than XMB already, because there's no more scrolling way over to this one thing, and then down to what subcategory you want, and then (to Sony's fault) having to remember which thing is under what. is it under Network? or is it under Playstation Network? oh, no, it's under Game. weird. the way this works is the settings stuff is all nested in one icon. the store, friends list, notifications, and settings icons are all up there and quickly accessible at any time regardless of what you're doing. hit O twice and then up to select one of those.
this one leads me to believe that the horizontal row is pretty much just the apps you have. the browser, Movies/Music Unlimited stuff, and what looks like another media app to the right are all right there being treated as equal as the games. i don't know how PSN games are going to work, or what happens when you amass a very large collection, but i think they'll figure out a way of making it easy and intuitive. after all, they listened to our request to add a folder feature on Vita.
COLORS:
as far as the blue is concerned, i think they're showing it that way initially because of branding. we all know they'll allow us to customize the look to some extent. if not with wallpapers (which would be nuts) then with color options or go the other direction and give us full blown dynamic themes from the get-go. if they had shown all this with a flat black background i think there would have been too many unfair comparisons to Metro or just the xbone. white would have been too bright, and too many with a game-specific background might give people the idea that there are themes or what have you. i'm sure we'll see more screenshots with more colors and, as the examples shown in this thread of different background possibilities, people will get more comfortable with it and it won't seem as sterile.