I adore reading books on my iPad. I have the iPad three and the first generation one (I write books about the iPad) and I've seen ebooks on the iPad mini; it too is very good for ebooks, though not quite as good as the retina screens of the iPad 3 and 4.
There are those who do not like the back lit LCD screen, and prefer the Kindle eink screen. I'm not one of them. Kindle screens for me are like trying to read a wet newspaper. The iPad mini while the screen is not a retina screen, has the advantage of being easier to hold in one hand, and it thus ideally suited to reading. I'd recommend an iPad for ebooks over other readers because it can read every conceivable kind of ebook, Kindle, epub, prc, .pdf, Nook, etc.