For about as long as Amazon has been selling Kindles of any sort, those of us who cover and comment on the company’s foray into mobile hardware have been trying to nail it down on actual sales. The guys in marketing over there must stay up nights trying to figure out new and twisted ways of indicating the device’s success without actually quantifying it. For years we suffered through silly games like characterizing digital book sales via these devices and all manner of “most gifted” and other proxies for hard (hell, even soft) numbers. The new version of the Amazon Metrics Muddle Game involves putting a number against an undifferentiated mass that also succeeds in telling us nothing. This season, we are told, Kindles were generally selling at a clip greater than 1 million a week. Of course, we don’t know how many of those are the less expensive sub-$100 e-ink readers and how many are the $200 Kindle Fires that grabbed everyone’s attention this holiday. Get ready for more Seattle-brewed squishy data points. According to the company’s year-end declaration yesterday, Kindle Fire maintained its place for 13 straight weeks as the best-selling, most gifted and most wished-for item on the world’s largest online retailer. The model has topped the Amazon charts since it was released. Right behind it in popularity were the Kindle Touch (#2) and Kindle (#3). The Fire is also the top-selling product across Amazon’s mobile @eb site and its apps. Overall, the Kindle Fire has to be counted a success among consumers. Of the more than 8,800 ratings for the item at Amazon’s site, half give it a full five out of five stars. And more than 7,000 of the 8,800 give the Fire four or five stars. Impressive. Even those with complaints (and there are many) cite “value” as the mitigating factor. I have spent much of my time with the Fire as a book and magazine reader. I found the same true with the Nook Color and Nook Tablet that I have been running through their paces. In my use at least, I find them reader-first devices that by their design segregate the app experience in ways that make me easily forget they really are mult-function tablets. I glean from the reviews that more than a few people are using Prime Instant Video and Netflix accounts frequently on the Fire, so it will be interesting to see whether video plays an even more important role on these screens than it does on the iPad. But it is clear from my early use across platforms that the Amazon and B&N entrants were built by companies with deep roots and interest in print media. The iPad was designed by a company that just designed a smartphone.