Perhaps "gimmick" is too strong a word. I don't mean to imply that it's just a marketing ploy with no real utility.
I'm just asking whether, at this time, in its current implementation, it's really worth all the hoopla. And it just seems to me that it carries - at the moment - as many compromises as improvements.
I assume that will change over time. But now is now.
Technology does not move forward if you sit and wait. Apple can't wait for developers to make Retina compatible apps, they have to put the technology out there to provide the incentive.
Over time, developers with either adapt of be left behind as other developers fill the gap.
In other words, the question you are asking is ridiculous. Of course this BRAND NEW display is not going to perform well in every case/app as there has to be development around it. However, just like the iPhone and now iPad this will change over time (and quite rapidly I think).