In theory, you should be able to add an indefinite amount of fan service without altering the quality. Saddlu, its often the case that fanservice is an indicator for poor script writing. So far this season is good and I don't think a little extra fanservice will hurt, but the elf annoys me. Call me racist, but elven women can't have a rack like that. She is a large breast pointy.
As for large breasts, they should be made of a fat like substance, not jello. The German chick's boobs go "boing", but in general keep their shape, Tifa's act more like partially filled watter balloons tied to her chest. That would be funny if its uncovered that she is as flat chested as Louise, but has water balloons to make up the difference.
There are three issues here:
1) I don't like large breast (Its just a preference)
2) I don't like water balloon breasts (its sickening)
3) Those with elven blood are delicate looking (in general Tifa is too full to be delicate)