I had a very brief play with the Aura yesterday, specifically the black, sorry Onyx, version.
Look and felt very nice in my hand and hands. Seemed as light and easy to hold as my Touch.
Sleep to read time is the same as the touch, pretty instantaneous. Read to sleep is about half a second slower than the touch, could be it was syncing at the time, as Wifi was enabled on the Aura but not the Touch, did not have time to check this fully.
Display seemed very clear and crisp.
Weight comparison between Touch and Aura is good, it felt only very, very slightly heavier (think it's meant to be 40 grams difference, but don't quote me on that).
That's about it, as said, it was a very quick hands-on (Thanks Jim!), but I think I would switch from my Touch to an Aura, and am considering doing so.
I do have questions in regards to the "limited edition" nature of the device, and I hopefully I may have answers on that at some point. Personally think it's just marketing talk to increase demand for the device.