Reaction after using it for a day, then seeing all these alternate designs: "I see what Apple did there."
After using it, I think there are subtle decisions being made over at Apple about these icons based on how end users perceive, differentiate, and use them not on a slide but on the screen, and how they will transition to them.
I think many of these design comps miss those experience and engagement rationales.
That said, I don't get Game Center. :-)