I would offer my impressions on the new Myspace, but I don't even understand how to sign up. The only available option on the page is to "go back to the old myspace".
I don't really think Myspace will take over the social networking field again. But then again I haven't seen it yet, as I stated above. So i'll leave my final opinion until later. But it's going to have to be really revolutionary for there to be a mass migration back from Facebook. And yes, a mass migration will be necessary for it to really be considered popular again, because the majority of people aren't going to try to keep up with 2 networking sites. Also, who knows how Myspace's past reputation will affect people's view of it now.
For me, I won't be using it unless everyone I know starts switching over. Obviously, because Myspace is nothing unless your social network is present.