The big difference between the iPad Mini and (most of) the regular iPads is the lack of Retina display
This is less of a problem if you're not actually used to the display, and is also less of an issue on the smaller screen. This has generally been the major criticism of the mini in most reviews.
iPad's big benefit is the size of the games / applications store - including comixology, Dark Horse, Marvel and DC apps (to be honest you only need the first two)
Kindle HD has more pixels in a similar size package so crisper images. I've no experience these myself.
I believe PJ and Art have both played with the Kindle as a comics reader...
This is less of a problem if you're not actually used to the display, and is also less of an issue on the smaller screen. This has generally been the major criticism of the mini in most reviews.
iPad's big benefit is the size of the games / applications store - including comixology, Dark Horse, Marvel and DC apps (to be honest you only need the first two)
Kindle HD has more pixels in a similar size package so crisper images. I've no experience these myself.
I believe PJ and Art have both played with the Kindle as a comics reader...