I think it depends on what accessories you plan to wear. If you are going to have bold accessories and a long veil, I would skip the belt. But, if you plan to go minimal like in the photo, then the belt is a nice little extra touch.
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In that case, I am going to go against my general rule of not liking belts, and vote for the belt! I think it adds a little something special, and it also accentuates your tiny little waist and gives you beautiful curves. You could also rock both looks by wearing the belt to only one part of the wedding (either wear it to the ceremony then take it off for the reception, or vice versa)!
So I normally despise belts with wedding dresses - I think they ruin the beautiful unbroken silhouette of dresses and often "chop brides in half" and make them look wider. I've never once seen a belt I thought actually looked good... until now!
The belt you have is really thin and not too over the top and dare I say looks pretty! It would help to get a comparison photo taken at the same angle with same hair/accessories, but I don't hate the belt... which probably says a lot.
So I could go either way. No belt is always a win for me but in this case I could be swayed to team belt.