I would disagree, it is not really controlled crying, more like gradual retreat. And you can take it as slowly as you are comfortable with.
We have been using the sleep sense programme with my son for the last week. He is just 4 months but we were getting caught in a feed to sleep cycle with him going from waking once in the night to 4/5/6 times and it often taking me nearly 1.5hrs to get him back to sleep.
The first few nights you are sat with them shushing, patting etc and you gradually move further away and have less interaction. We were back to only one feed per night within 2 nights and DS is so much happier in the day. He still only takes 30 minute naps, but at least now he settles within a couple of minutes in his cot for them rather than me jostling a buggy around in my sleep deprived state trying to get him to sleep.
As with all these things, you have to commit to it and it will work. Some methods are quicker than others. I was on the verge of losing the plot and after a day where I was distraught, sobbing down the phone to my DH at 9am and him racing home from work, we had to try something.
We used the programme through a consultant and some of the boundaries were softer than the sleep sense paperwork sets out.
Happy to answer any questions you have. It has quite possibly saved my sanity.