You would have to have a late 2009 Macbook with 5.1.1, and have Kindle to give me an opinion necessarily. In the mean time I will call up AppleCare and ask them before I actually prurchase the book. I can buy it from Amazon(at their profit) or I can buy it at iTunes(at their profit) buy the bottom line is that I want to read it on my Macbook with Kindle.
You can't read ibooks from Apple in a Kindle app - ebooks tend to have digital rights management on them, so ibooks from Apple can only be read in the iBooks app on an iPad, iPhone and iPod Touch (they can't currently be read on a computer), and ebooks from Amazon can only be read on their Kindle ereaders and apps.
You should be able to download it from the ibookstore and read it in the iBooks app - the left-hand side of the app's description page in the store lists its current requirements as iOS 5+. If you go into the ibookstore in the iBooks app on your phone are you able to download the sample directly into the app ?
But if you also want to be able to read it on your Mac then you should buy it from Amazon as they have a Kindle for Mac app in the Mac App Store.