No. Be-all end-all, no. Do they have protein in a small light package? Yes.

They’re a quick, usually sweet, snack for on the go. Personally, I’d rather have trail mix or a Snickers.

They are little more than glorified candy bars, but don’t taste as good.

It depends on the ones you get. The term “protein bars” tends to cover a whole range of types. I am hypoglycemic, I find that the ones that are nut and grain intensive are really good for staving off goofiness when I am late for a meal.
Way back in the day I used to make my own, but it was really messy, now I buy them.

Some are literally candy bars. Others are pretty damn good and healthy. I still love plain old cliff bars for when I’m doing intense exercise. They just work by providing you with sustained energy. Meal replacement bars are something else. Diet bars are something else also. All fall under the “protein bar” umbrella.

I read somewhere that all those protein bars etc only had about 5% nutrition the rest fillers and sugars.