I don't watch much live TV, yet I think the TV integration is cool. The fantasy sports stuff is just one possibility, it was hinted at during the presentation, but imagine what could be done for debates or less interesting award shows.
The newer Kinect seems real neat, although I do fear what it could be used for, (emotion tracking during tv ads?)
I think it's too early to speculate on "destroying the used game market" as MS has been very vague on the exact details. Not an issue for Steam for what it's worth.
Skype integration does seem cool, after moving away from home, it's nice to Skype with the family back home, and doing it on a TV seems more personal to me than an iPad or laptop.
The instant switching feature seems cool too, will have to see how it actually performs. Right now on my tv there is 2-3 second delay while switching inputs. Quite a first world problem, but cool that they are addressing it.
To me it didn't seem like PS4 brought much new to the table, while XO seems a bit more of an evolution of the last console.