Never tried it but it's in the spinach family, not mustards.

I grew a few different colored orachs this spring, green, yellow and red. The flavor is somewhat similar to spinach, but I didn't think it tasted as good as other greens that I was growing, chard, etc. It's marketed as a warm weather alternative to spinach because it won't bolt in the heat, but the flavor is best in cool weather. It got too strong in summer.

I sell at a farmers' market and a few people bought orach once or twice, but I never heard any rave reviews. I started putting it in salad mix, a few of the varieties I grew had very vibrant coloring that looked very nice in a salad, but that's about it. I'm not sure that I'll grow it again.

Yes, it is in the Chenopodiaceae, not the Brassicaceae. It self sows all over my allotment. I use a few baby leaves in early salads when there's not much about but otherwise don't bother to pick it. Chard also self sows and is far more flavoursome imo. and easier to harvest (bigger leaves). I've also added the fresh seed pods to salads but they were uninspiring and tough. It's so easy to grow you've nothing to lose trying it - it requires no care at all.