I've received several of them as gifts & the recipes - thankfully - do seem to run true to form. Nothing's more frustrating than trying a recipe that just doesn't work no matter how you try to tweak it. Makes you wonder how much "testing" some of these cookbook authors/editors actually do sometimes.
I also like the fact that many of the recipes use interesting ingredients, but not so "interesting" that they're impossible to find or use a substitute for.
How good they are depends in large part upon who wrote them. Each one is different. If you have comprehensive books on the subjects already, you probably don't need them, but when did that ever stop us from buying a cookbook?
Wine is the food that completes the meal.