There's nothing bitchy about sharing an opinion when that's exactly what was asked for. The OP asked for people's thoughts, which suggests she's on the fence about it. If you ask for opinions, you have to be prepared for a range of responses, not just the ones that agree with your own view.
This dress is something I would wear to my child's birthday party in a garden (apart from the polyester fabric), not something I would expect to see on an older woman or a mother of the bride.
In my opinion, this is the kind of dress that won't age well. When people look back at wedding photos 40 years from now, I don't think it will have the classic, enduring appeal that many mothers of the bride usually aim for. It feels very trend-driven rather than sophisticated and enduring.