As for fitting, I'm pretty normal, use anything from S300, Project X, Rifle 6.0, I'm not strong enough for anything firmer and hit a normal ball flight. All stock lie and length, though apparently the Nike's are one degree upright and 1/4 inch longer but I didn't notice.
I've spent a ridiculous amount of time on flightscopes, figure it's more important for driver, but having said that I'm average height and weight so can use most clubs without any tweaking. The Mizuno optimizer suggests a softer shaft but interestingly I got a different reading when using outside (IE hitting on grass and taking divots). Out of all the shafts I prefer the S300. Maybe it's because I've been using them since I was 15 (in various clubs, I'm now 29) but they feel fine. My brother's soft stepped X100's are too stiff for me, I hit them ok, but low and could not turn them over.
How did they feel? To be honest, I've really disliked Nike equipment, not for any reason really. However this particular model came pretty highly endorsed from my brother who used the demo set a week earlier. The two long irons make quite an uncanny noise, a clink sound, and the rest are more normal. However they seemed to fly very straight and a little higher for me. I was really pleased with them. The feel as soft as the Mizuno's, but again, hard to tell unless one hits them side by side at the range. They are by far the best looking Nike irons I've seen, no garish graphics either. A quick re-grip to full cord Lamkins (need cord grips for our wet winters) and they're ready. So I played ok, 5 over, 29 putts and hit some really nice iron shots. The long irons are easy to get up and they all compact behind the ball.
Here are some pics...