The less saturated screen is probably a decision made by Apple to balance cost, battery life and size. Most people will be happy with the compromise. Some won't but they'll be in the minority I'd think.
I read somewhere that the iPad air looked almost too saturated and a smaller tablet would amplify that issue. If that is true, then I can understand the logic.
I've said this before and perhaps I'm not as picky as some people but my screen is gorgeous. No yellow and I've not really noticed any saturation issues.
The contrast seems seems a tad duller but not enough for me to complain about, more like an observation.