In my neverending quest to own virtually every ereader imaginable (well, at least ones I can buy in a store), I recently decided to buy the Aura HD made by Kobo. Naturally, 2 days before the announcement of the Aura, I had just purchased the Kobo Glo. I've always liked the Kobo devices more than the Kindle devices, for several reasons: I prefer the design of the Kobo, they track reading stats, epub support, WAY MORE options for customizing the reading experience, ability to add custom fonts, and a few more. I bought the Glo after having tried, and returned, my 3rd Kindle Paperwhite because the lighting on every one I tried was crappy. Anyway, I bought the Glo, then shortly afterwards the Aura HD was announced. It peaked my interested enough for me to order one, and after 3 weeks, it finally arrived and I've been using it for about 2 weeks (and I've returned the Glo, since I no longer needed it thanks to the Aura).
The primary things the device has over the Glo, and most other e-ink readers, are the screen size and the DPI. Instead of the standard 6" screen, the Aura HD offers a 6.8" screen at a resolution of 265 DPI. The Kindle PW and the Kobo Glo have a DPI closer to 212 I think, making the DPI of the Aura about the same as the iPad 3 & iPad 4. So does the extra 0.8" of screen real estate, along with the increased DIP make the device worth the extra $40 over the competition? I think so. To me, the screen is noticeably bigger, and the higher DPI is even more evident. I mostly read fiction that I've purchased from the Kindle store and converted to epub thanks to Calibre. Technical books I usually read on my iPad mini, as the bigger screen is almost a necessity for reading technical books. For fiction reading, the Aura HD is definitely the best e-reader I've ever owned (and I've owned around 12 different e-ink devices at this point). The text is super-sharp, and the ComfortLight blows the Kindle Paperwhite lighting away..its not even in the same class to me. All 3 KPW that I tried had blotchy lighting that I honestly thought was terrible. The lighting on the Aura is nice and even, and adjustable in 1% or 10% increments. Thus you can really fine tune the amount of light to fit your environment. My only complaint with the Aura is the shell..its a hard plastic shell that can be a bit slick. The previous Kobo devices I owned had a nice, soft rubber exterior which is much more comfortable, and less slippery, than the Aura. That casing on the Aura almost makes it feel a bit cheap. But other than that, I think the Aura is a fantastic device. I think the only thing Amazon could do to lure me away this fall would be to offer a Kindle with an even larger screen size and similar customizable reading options (which will probably never happen). I would love to see an e-ink device with the same screen size as the iPad mini.
So, would I recommend the Aura HD? Absolutely, though if you are hoping the larger size makes pdf reading a lot easier, you might be disappointed. I don't read many pdf's, but I did test a couple. While there was an improvement, there wasn't enough of one to make me want to read a pdf on the Aura instead of the iPad mini. But for plain old epub reading, I think this is the best device you can buy, at least for now. I do think the extra $40 is worth it, and I'm really happy with my purchase. There were lots of complaints with Kobo's customer service during the initial launch period (people getting charged twice, orders lost, customer service not knowing the order status, etc), but I think things have improved after the initial rush of orders. If you buy a lot of epubs, or know how to convert your kindle files to epub, or you read a lot and the bigger & better screen appeals to you..I would think you would find a lot to like about this device.