IPS displays - maybe, but not all IPS displays. I work on IPS displays since 12 years and there are very different in quality. The best example for this is Samsung screen on my retina MBP 15" (which is nearly perfect concerning retention) vs mass of LG screens having ghosting as their brand feature.
Same goes for the ipad screens. Ipad 3 (Samsung) has no retention, where ipad 4 with LG matrix does.
Please do not be blind for Apple marketing propaganda, - of course they will tell you, that that is normal and not a issue, especially, when they just lost Samsung as their supplier. What are you expect them to say? "Sorry, our every second ipad has an inferior display. so we hope, that you will get the right ones."?
It is not about praising the Samsung displays, but much more about the issues on the LG ones. IPS alone is no panacea.