Are they any good for what?

If you want reasonable answers, a lot more detail is needed.  Age, why you
want to see one, medical history, etc, etc, etc.

I have a counterexample to Zee's "No. They aren't any good."

My office partner had suffered chronic back pain for
about a decade, had always been turned away by MD's
with "there's nothing wrong with you".

When I smirked as he told of going to a chiropractor
out of desperation, he told me "You might be interested
in what he told me: You're very sick but there's nothing
I can do for you.  Get yourself to a MD and if he tells
you there's nothing wrong then try again to find a
competent one."

Two MDs later, an orthopedic surgeon checked him into
the main local hospital looking for spinal problems.
Admissions blood work set off the alarms, soon they found
the prostate cancer which had already been in his bones
too long.  He didn't last a year despite chemo and
starting a "medicinal" macrobiotic diet.

Annual checkups including DREs didn't help (I don't know
if he had PSAs, he died over ten years ago).  The hospital
staff commented that they didn't kow how a DRE could
have missed it: "big as a grapefruit, hard as a rock."

The chiropractor recognised that there was a problem.
This was real relief.  Perhaps the next MD would have
been as useful.

Ed