We used Millpond for DS1. He was 6 months (when we started - 6 week package). They gave us a gradual retreat programme to follow - I have outlined it in detail on another thread here (www.mumsnet.com/Talk/sleep/1324357-Anyone-had-a-good-sleeper-regress-What-did-you-do.
They gave us detailed advice about daytime routine, feeding etc, not just night time sleep. We had to keep a sleep diary for a week before we started. When we got the sleep programme from them, my initial reaction was that it was very standardised and not tailored to us / DS. I was a bit disappointed. However we followed it anyway, because we had paid the money by then, and my goodness it worked. DS1 was a truly appalling sleeper (I looked back at the sleep diary recently - then night before we started the Millpond programme, he woke up 13 times!). Things improved almost immediately - from night one we went down to 3ish night wakings, and on night 7 he slept through from his dreamfeed until 7am. He's been a great sleeper ever since, a model 7 - 7 child (sleepwise, anyway!!), great napper, and we have only very rarely had bedtime issues.
I'm not sure that Millpond tell you anything you can't find out for yourself from books, but they do kind of piece it all together for you. For me the main benefit was the weekly telephone consultations when I was so bloody sleep deprived that if I hadn't known I was going to have to have a conversation with our sleep consultant, I would just have given up on about night 2 and gone back to him sleeping in with us. And also knowing that we'd paid the money kept me going!
I'm not going to pretend that there was no crying involved - night one was quite bad and involved 1.5 hours of screaming, but he was cuddled all of the time, so to me it didn't feel as bad as cc.
We are considering going back to Millpond with DS2 if we can't sort him out ourselves - even technically having done it before I can't seem to get DS2 to sleep well, and I wouldn't hesitate to go back to Millpond for advice if we're still in the same position in a month.