I don't like the high cut ( above knee) slit for a wedding. That is club wear, not a formal and after six look, and certainly not day wear. Weddings are usually multigenerational and more formal and classy. I don't think deep plunging necklines, and super high slits, which are not at all formal wear, are appropriate.
It looks very pretty! It looks very boho to me, like maybe for a forest or nature wedding. Definitely more modern, but there is nothing wrong with that! The sleeves look like they have a train of their own, which might be a little annoying, but it is very unique and I love that!