I like the dress. It has a lot of style, but two things concern me. First is the length. You have awesome legs to pull it off with, but Seattle is not warm in December. Also, I think it would need a warm pashima or something else to keep warm. I agree with the others, why sleeveless in December?!? I mean, not all of us live in SoCal or Florida!
As a seperate aside, do you need sparkly wear? Basically, would you wear this again, perhaps for New Year's or other Christmas festivities? it does not fit into your Opera capsule, and I wonder where else it would work for you.
Perhaps you could add a sparkly scarf of tank to one of your already fab ensembles to get the holiday sparkle but still have wearablity again.