Got mine yesterday and very happy with it. No pinholes and the screen looks good to my eyes - which are the only ones that matter.
Spent some time today comparing it to my Kindle touch and I prefer it to that. I think the contrast is better. The non-text looks yellow-ish rather than grey-ish. Also compared it against my Kobo Aura HD, specifically the light. The light is whiter, less blue. It's also fainter at the lowest setting but brighter at the highest. On the Aura I can comfortably read in a dark room at 1% - I need it on at least 4 or 5 (of the 22 scale) on the Kindle, but that's ok. I'd prefer it if I could switch it completely off.
Like my touch it feels fast and responsive. Even my Aura, with its faster processor than the Mini or Kobo touch, doesn't always feel that fast. I do like the Kindle firmware design.
The only odd thing I've seen is with the page refresh. I've got it with the default setting i.e. refresh every page is OFF. However I've noticed on a couple of books that I can have several pages in a row where it refreshes every page (such that I thought the setting was ON) and then it won't for several pages. I guess it's to do with the contents of the page and how it calculates what's changed - there must be a threshold at which it decides it's worth doing the whole page.
The one thing I miss from my Kobo devices is the ability to download books via the web browser.
Hmm. Was just in the process of checking that that last statement is still true and the Kindle froze on me trying to update a web page. I guess that's why it's 'expermiental'.