I quite like the new decompiling feature, specially because it is such a seamless experience. It would be nice to have a way to navigate to IL instead of to code? This is definitely a nice to have but it would be useful in certain cases. In case it is not clear, I would mainly be interested in navigating to the IL of my code.
I am quite happy with the improvements in 6.0 more specifically with the treatment of strings (as in string.format) and in several other details that together contribute to a better coding experience. This EAP also seems to be more stable than the latest one. Congratulations!
Finally, I don't see any difference in terms of performance (when compared to 5.1.x I was using before) but it has never been too bad for me and it is usable in a 25+ projects solution (WPF application). The worst I have is whenever I recompile the whole solution I get a delay of maybe two seconds when I Ctrl+tab from a cs file to a xaml file. This delay goes down to maybe half a second subsequently.