A lot of folks keep thinking this relationship is out of left field, but twice in TOS Uhura was flirting with Spock, and she asked him for lessons on the vulcan harp!
I think it works. It's exploring a new dimension of Spock that Nimoy's take didn't venture in to. It also expands Uhura's role when she was mostly the ship secretary and occasional background character of the original lineup. I accept the pairing and I'm interested to see where it goes.
Oh... Carol mentioning Christine in passing and Kirk not getting it, I wonder if that was a 'take that' to those fans who were harping so hard that Spock shouldn't be with anyone else.