I also suffer from Fibromyalgia and have nerve damage in the spine which causes burning and spasms in my legs and feet. I find that I can get pretty stressed with the amount of pain, and lack of sleep due to the pain. What MJ does for me is it reduces the pain and allows me to cope with the pain. There has been the odd occasion where I have been so stoned that I have been pain free, but mostly it allows me to relax enough, drift and forget about it for a while. It helps me relax my muscles and therefore less stressed, and it helps me get to sleep.
I have found that if I start smoking about 6 pm, by 2 am I am ready to go to bed. I try not to smoke during the day as that would be unfair on my employers who have been really supportive of me and I doubt that I would get much done if I did.
I think the best thing for me has been the opening of the mind, it actually makes me more able to recognise my own thoughts and therefore stop the negative thinking associated with chronic pain.
The only things I don't like are the odd experince of panic, I feel like I am going to collpase but that might be just my muscles in my chest relaxing, and all the munchies. I put on far to much weight with the prescribed drugs, and because of the lack of mobility, have been unable to lose the weight again.
For me the benefits far outweigh the negatives.