I dont think retreat was ever an option. They would have lost a lot of men, not just from the weather conditions and possible attacks, but from starvation. They also would have lost time. Time they didnt have. It really is a now or never situation.
So instead of a large part or his entire army of men dying slowly, he decided to give up his daughter. It makes sense.
That being said, he is power hungry and delusional. He wants to be king for his own sake, but also for his faith and his belief in Melisandre's visions or whatever. He thinks the way he's going is the only way to defeat the white walkers.
Somehow the internet believes he had no emotions about it, that he didnt give a second thought to sacrificing his daughter. Stannis isnt the type to start crying and going into hysterics. I suppose for some people thats their only way to show their feelings. He seemed pretty bummed out to me.
Also, a lot of people were really critical of the dragon cg. Am I missing something? I thought it was great. They looked as good as dragons are going to look. Smaug wasnt any better. That shit was awesome.
I dont know what people expected. Its not like making apes in the new Planet of The Apes movies, thos ehave a real life reference. They have guidelines to follow, so it's easier to do. Dragons are fucking make believe. They can look however people want them to look.
While I have my own criticisms about cg(mostly that its used too frequently and liberally), that shit is a lot of work. And most importantly, it tends to be made by people who have a passion for it. Thats why they get paid shit for it. I cant stand people making fun of it. Thats a shitty attitude to have.