This icon set is personally my favorite metro icon set out there. Everything about this is amazing.
Let's start with the vision, as in what it looks like. The icons look amazing, anywhere you put them. The color selections are very wise. Although, I kind of think that there is a bit too many light blue colored icons. The square shape of the icons make them look great when they are together. These icons are also a perfect fit with Windows 8.
Well, about originality. These icons are not exactly a new idea. They are made for the well-known Metro UI that came with Windows 8. Still, this icon sets is a very popular one, and many of these icons have never been seen before.
I don't know about what technique was used, but whatever technique was used, it seems that you knew what you were doing, as it turned out great. If I look closely at the icons, none of them look stretched. The white icons are perfectly centered on their tile.
Impact? Well, I'm pretty sure that icons aren't made to "evoke strong emotions", which is what impact is for. I'm going to talk about a different impact. These icons have become very popular. Many, many, websites use them (some without giving credit ). I also think that these icons look amazing with Rocketdock, and they're the only reason I downloaded Rocketdock.
Overall, I think you did a great, splendid, job on these icons. If there weren't categories, I would have given you a 5 star overall! Keep creating icons!
Yea, I agree with you that there are too many light blue icons, but blue is what I think of when I think Windows, generally. I made a lot of them that color so people can have the option to color them however they like as I don't know what to color each of the blue icons.