One further addition to Yorkshire Pudding's post is that these policies are often sold on the basis that you can reduce the monthly contribution at any time. This part is true, but the bit that you are not told (except perhaps in very small print) is that the charges will continue to be calculated on the basis of the original contribution.
So if for example you take out a 20-year plan saving $2000 per month, and subsequently drop down to $1000 per month, the charges will continue to be levied as if you were still saving $2000 per month.
Appalling stuff really.