Just finished restoring my 64gb model from my ipad backup.
Ordered mine from Apple on pre-order day but that order was still showing as ships in two weeks with a deliver of 15th november, by chance the local apple reseller got one 64gb wifi black in (said he got very few black model period) and so he held it for me this morning as those who has pre-booked with him had looked for 16gb mostly (which again he got very limited stock).
So impressions...
Yes the screen is noticeably non retina, there is no getting away from it.
But it is indeed better than the original ipad and ipad 2.
The weight and feel of the device is fantastic. Prefer it already.
As for speed and performance, there is little difference with ipad 3 starting applications and such. I opened a couple of applications side by side with my ipad 3 and couldn't spot any real difference (milliseconds).
Now to memory test because of the 512mb...
Safari, no checker-boarding

yay!
1) im loading up MacRumors and started this post.. Before finishing I select all and copy just in case...
2) Then opened new tab and opened The Verge & another with Engadget and no checkerboarding once both pages finished loading.
3) Loaded an new article in Engadget and the verge pages
4) Back to macrumors page/tab to update this post and YAY it didn't reload, so the 512mb I was worried about seems to be not too an issue after all.
So far delighted.
I'm going to give my iPad 3 to a relative as a christmas present. The iPad mini for me and my usage is the perfect size and weight with minimal sacrifices that had to be done as 1) no 2048x1536 7.9" screens exist, 2) the A5X or A6X in this device would require more power = thicker device, heavier and a lot less battery life.
So the trade off, for the moment until technology catches up is worth it for me.
Couldn't get a nice smart cover today as they had not arrived in the store though. So will have to source a smart-cover elsewhere.
Edit update....
Typing on this in portrait mode is much better I find too.