I'm currently running a Sprint Galaxy SII and love it. This phone does not seem remarkably different so far but it does have some advanced features that seem cool. I'm not crazy about the color choices for this phone but I'll reserve judgement until I can hold one in my hand. If I decide I can't live without it, I can give my SII to my wife.
As a fan of black (or, hey, gunmetal grey works too) phones, I understand your questioning about Samsung's color choices. That said, the blue SIII does look very nice, to the point that I'm not missing having a black phone. The shade of blue is dark enough that the phone looks good in it, versus some lighter, chintzier tint.