Great outfits! 1, 4 and 5 are so perfect. Weather you show that belt or not in 4-5, it looks fantastic. 1 is simply too cute and dynamic.
I have to tell you, from the photos, I don't think this dress does much for you. I studied the pics a little with morning coffee to figure out what it is that make me think this. This is what I see:
1. It sorts of dangles awkwardly at the hem and bunches strangely at the bust. You still look ok because you have a fit body, but does it flatter you?
2. You pinpointed the black and I think you are right, however not the color black per say but this specific shiny material in black is what is the problem. I'm sure you wear black well, but it would have to be deep and matte. Your hair is beautifully rich in color, it is shiny, and this dress in competing with it kills the effect to my point of view.
It's hard for a lot of fair skinned people to look good in a glistening black. The light hits it in such a way that it doesn't provide enough contrast. I think that on the other hand it might look sensational on dark skin. I may be wrong.
What I wrote above might explain why outfit 3 looks a bit better than outfit 2: the belt, in a deeper black, and the shoes, in a matte black, provide balance, and the eye travels more comfortably up and down. Those elements, and the cute jacket, help the viewer forget about the unfortunate dress' s luster. In 2, the bright elements only serve to bring attention to the dress and amplify its color.
Notwithstanding I really dig your style in the other outfits.
OK that was my two cents. Have a great day/evening/night!