I have had fibro for 20 years, and about 3 years ago was diagnosed with inattentive ADD. I was put on ritalin and discovered that it helped some of the fibro symptoms, in addition to ADD symptoms. It helps clear the "fibro fog", helps with fatigue, has a mild analgesic effect, and is slightly, although temporarily, mood enhancing. It does affect each person differently, and different stimulants work in different ways. Stimulants can be addicting when abused(i.e. taking large doses to get "high"). When used as prescribed they are typically not addicting. Not in my case, anyway. I take 20mg sustained release 2 or 3 times a day depending on how I feel. It makes me alert, focused, but not speedy or jittery. It smooths me out, and relaxes tense muscles, and I sleep better having taken it. If I run out of it, I don't have withdrawal symptoms...it just wears out of my system and I slowly go back to being the way I was before I took it

It has made me feel more "normal" than any of the antidepressants that I've been put on, with none of the side effects

But this is just my experience. Check out the following website for more info on stimulants and FM.
http://www.add-fibromyalgia.com/
Hope this helps.