I suppose it does depend on context, but in my personal experience it was a complete and total waste of time and money. Mediator was clearly a sexist pig and directed the "agreement" to my ex's benefit, putting my daughter and I into a really crappy custody arrangement where she was fucking miserable for the next three years until I took the fuckwit back to court and got residential custody.
I accept not everyone has such a negative experience with it, though.