I have been using glucosamine almost for 10 years now. Used to have quite noticeable knee pain and with the age it started with the other knee as well. It was a life changing for as now I dont have any complaints any more. As soon as you start taking it, you will notice almost immediate improvement in your mobility and the effect is cumulative.
I guess they are good, but from the absorbabilty point of view, I switched towards vitamin D, apple cyder vinegar (the citric acid helps with this!!), K2, magnesium and the keto-paleo diet with max 20 grams of carbs a day.