My reasons for considering it immoral are that it concentrates too much power over the circumstances of the beginning of a person's life in the hands of other people, and that it's a means of assembling a person like a product rather than allowing a person to eventuate out of some sort of preexisting human relationship. I'm aware that these are unfashionable concerns to have. I don't consider it notably more immoral than other forms of gestational surrogacy. TNF would probably count this as hokey religious garbage and I won't deny that my religious convictions influence my viewpoint but I hope it escapes being considered anti-science or (inherently) right-wing.
I do wonder if you actually meant to make the comparison between cloning and ‘gestational surrogacy’ given what gestational surrogacy actually encompasses. I find it curious that a trans woman, a member of the LGBT community and a Christian (with a nod to the conception of Christ) would take issue with a woman carrying and delivering a baby for someone else. If a woman does not have a uterus, or has issues with carrying a child I really struggle to see how someone else carrying that child is ‘assembling a person like a product.’