I have a Kobo Aura HD and I find it a little better for actually reading ebooks than the Kindle. But it's not a Kindle killer. I'm comparing it with my Kindle Paperwhite 3G. I also have a tablet, but I still like e-ink with a backlight.
I say it's better for actually reading because you can select the font, paragraph justification and line spacing. That would be in addition to the being able to select the font size like the Kindle can. It has space for more books, 4gb on board + up to 32 gb on a micro SD card and it manages battery life better. I use airplane mode on the Kindle to get better battery life, but on the Kobo, I don't have to bother. The fact that both devices are e-ink readers with a backlight seriously limits my options.
But, I say it's not a Kindle killer because the Kindle store is much better. So is the ability to load books to the Amazon cloud via e-mail. The fact that both the Kindle and Kobo readers are partly subsidized by their online stores means I'm not holding my breath looking for the next Kindle killer. I'm in Canada, and I believe that still rules out the Nook (B&N) store.
Going back to the original article, the Kindle store is much better than the Google Play store and iBooks as well. Synching annotations with your laptop or tablet is automatic as long as WiFi is enabled. There's just no voice input option.