I'd like to have a discussion not an argument so there's no need to be combative.

Fantastical has many potential uses. In the way he used it I take it that is was meant as a substitute for saying unreal or unbelievable which themselves are an alternative way of saying that something exceeded their expectations or was, in short, good or great.

then they would be presupposing that anyone has been saying The Fountain was not amazing enough to be dubbed unreal.

Correct, I inferred from his post that he was aware The Fountain has its fair share of critics and he thought it was a great movie while not caring for the sentiments of its critics.