The fact that you can now directly connect signal handlers without using moc to generate them is great. I vastly prefer this form from previously using libsigc++ and boost::signal; it's nice to see Qt getting the same type-safe handler style, and even nicer to see that you can use C++11 lambdas! I hated runtime exceptions when the signatures don't match, since it's entirely possible to catch this at compile time!
I assume you still need moc for SLOTs though, which if true is a shame. It would be nice to remove the need for moc entirely (or as much as is possible).
The other feature of note for me is the OpenGL work. Can anyone confirm if it's possible to build Qt to run directly on the framebuffer with a modern DRI2/KVM setup with accelereted GL? Or is X or wayland a hard requirement?