Depending on ingredients they normally taste like a nutty stuffing so what's not to like if you like stuffing?
Usual ingredients- Chopped/ground nuts, onions, some veg liked Chopped mushrooms or grated Carrots or roasted squash, maybe a cheese layer if not vegan , some herbs, some breadcrumbs. I like them quite chunky.
The M&S one is nice and the meat eaters have a bit like stuffing.
Rose Elliott clearly nailed it years ago. We used to do her chestnut and redwine en croute but prefer somewithout pastry now.
I make a couple of the Delia parsnip roulades every year as for a few of the guests it's not Christmas without it. It has many steps but comes together impressively at the end. My sincere advice is do not attempt it on Christmas day. It's definitely a day before task as you need space and pans to make it.