Hypnobirthing didn't work for me. I bought into it and honestly believed I could get through without anything stronger than gas and air - I'm no wimp!
But, when it came to labour, the pain (probably because DS was back to back) was far too intensely overwhelming. Ended up with a very long labour, culminating in an epidural, failed ventouse and forceps.
At the same time as I was preparing for my first labour, two of my close friends also tried hypnobirthing. One "just" did the cds, like me, the other had a private instructor.
First friend said it was partly helpful in the very early stages, but she ended up with an emergency section under general anaesthetic.
The other friend said it was no use at all in terms of pain relief or distraction during labour (very fast, intense yet straightforward vaginal birth) but she found some of the techniques calming in the difficult first few weeks, when she was sleep deprived and struggling with breastfeeding.
None of us have done - or are planning to do - hypnobirthing in our subsequent labours.