I would say, like many other issues that have to do with scientific advancements, it is not unethical in and of itself. It all depends on the situation.
I don't agree with unnamed, anonymous donors being used, because that can bring to many problems later on. Of these problems include medical issues that were not taken into consideration at the time of donation, and therefore, not screened; as well as the issue of the child and the father/mother not knowing who each other are, which has caused issues in a number of cases.
But I see no issue with allowing an otherwise infertile couple to have children. I think that ability is really a gift of God.
As the OP specifically brought up lose of embryos and potential harm to the mother due to IVF, I would like to point out that natural reproduction also can be tremendously harmful (most often moreso, due to the already high amount of medical attention for IVD compared to that of a couple reproducing naturally). As well as the high number of miscarriages that take place early in pregnancy (often before signs of pregnancy, appearing as a heavy menstraul cycle to most women [I am so sorry if that is too graphic, let me know and it will be edited!]).
So I see no reason to determine it unethical in itself.