I'll upgrade eventually. In the last few hours, two music videos became available. I want all my music.
I'm sick of paying extra for music I already own. I will upgrade only if I really need it or if I becomes free.
I'v already started buying most of my songs from Amazon where I get DRM free MP3 to begin with. Yah I know, AAC is superior, blah, blah.
And yes, I'm tired of paying for songs I've already bought. I'll probably give in and upgrade to plus, but for me, it's a non-trivial amount $$'s for the large number of AAC/DRM songs I've already bought from iTunes.
Not until they offer a way to upgrade parts of the library, and not just all of it. There's stuff it wants me to pay to upgrade that I don't even have in my library any more.