My experience with one chiropractor was positive. I had been lifting heavy at the gym for a while and began to have some problems, primarily sciatica. I was talking to my trainer and he pointed to a gentleman who was in the middle of his training routine and said "go see that guy." He allowed me to interrupt and after I described my issue he suggested that I come to his office. I should note that he was a sports chiro. None of the new age quackery that so many chiropractors seem to adhere to. His manipulations worked well for me. There was some immediate relief followed by further gradual improvement after a couple of weeks of unchecked torment.
Note that I mentioned that the experience with that one chiro was positive. I also have had first hand experience with the new age quackery I previously described. This one used the x-ray machine, which the first did not use, then went on to tell me that I had major vertebral fusion in my neck that if not treated would only get worse and would pretty much render me immobile later in life. He then spoke of a patient who could have had what was terminal heart disease cured if he had undergone manipulations over time. At this, I was done. I left and did not return.