They really do want you to sign in for all this.
That's putting it mildly. I was already signed in on YouTube (testing the waters, you might say), so I went to check the privacy options first, and I almost felt like I needed my lawyer to review the choices. They want to have more public activity by default than I'm comfortable with, and they are very much pushing social sharing and integration with other social services in many not-so-subtle ways.
This has been sneaking up, but now it's very methodical. I notice, eg, that there's a video on Google+ circles in the "Science and Technology" most viewed videos, and there's a 'connect to Facebook' link at the top of my main menu. They want maximum visibility when I Like or Share anything. Until they get rid of those cutesy hearts, though, I'm liable not to like anything on the site. ;)
If you take the tour to check out the new features, you get a message that I feel is revealing....
Click Home once you have subscribed
to 3 Channels. That's it!
I'm not sure what happens if you don't subscribe to 3 Channels. The integration of channels, individually customizable, into the home page is good... but, overall, there's something very "busy" about the new Home page design. I think it's got to do with the very light weight and small size of the body font coupled with the multiple distractions for the eye. I suspect this will go through various stages of redesign.
Individual video pages not much different than before, and I find that the slightly grayed default background actually helps reduce eye fatigue when you're not watching at full screen.
[edited by: eelixduppy at 8:05 pm (utc) on Dec 3, 2011]