Methadone has helped many get off opiates, I personally know of two addicted loved ones of friends of mine who were quite successful using methadone for about a year and then withdrawing from it, all under doctor's supervision.
Like any substance, it can be abused and often is. But it can be a great help as well.
There's not much to talk about with methadone, it is one of many optional treatments for getting off opiates.
I pray your son finds the same success as my two friend's daughters did.
Hugs