I haven't tried cranial, although I've been thinking about it. My boss suffered a severe concussion last year, and since has had symptoms similar to migraine, without actually having one - she gets serious headaches, is unable to use the computer for more than half hour without one coming on, is unable to concentrate for any length of time, and so on.....
She's been going for cranial, and has found that it really helps her. The day after treatment she generally isn't much good for anything - very tired and washed out. After that she perks up, and seems to be getting better with everyone she goes for.
As for what they do, I'm not entirely sure, but she's told me they put their hands on your skull, and just gently move them over it. Apparently they're moving things, but she said you can't tell what they're doing, the movements are so small and soft, very gentle.
My mum's also been - she has something called arachnoid cysts, which are cysts in the veiny covering of your brain. They are totally benign, and lots of people are born with them and never know. Unfortunately, mum's were disturbed by a whiplash from a car accident, and every now and then leak, causing unbelievable headaches. They thought she was having haemorrages! It's manageable now, and she leads a totally normal life, but an old friend of hers practices cranial and offered treatment. She loves it!
Hope this helps a bit? I'll let you know if I go for any