I've been using this product for about 3 years now. As with many supplements you might not feel a difference when you start taking it - I certainly didn't. What I did do though after a few months was a negative test where I quit using it. Then I really noticed a crash in my energy level. After starting to use it again I felt fine. I've done the negative test three times now with the same result each time. It works for me regarding my energy level and I highly recommend it.

Some people don't prefer this brown/black color or talked about fading, pick-up of dirt, etc. Also yes it's canvas.