IMO the retina screen is a big reason to upgrade from the 2 (and is the reason I waited for the 3rd gen model). I pretty much use my iPad exclusively for reading text of some format--web pages, text-based services like Facebook and Reddit, books, etc. (with the occasional YouTube or Netflix video thrown in)--and having that extra clarity as compared to the first two versions is crucial for me.

It's now that I don't really feel any compelling reason to upgrade -- even with iOS7 the interface is plenty fast enough, and I don't use it for games so any increases in performance wouldn't really matter to me.