Does the IOS7 download affect any apps?

No it depends on how many apps have.

My sister got it and all the apps look cartoon like and not nice. Really the update is ugly.

I am not getting it. Though,from the last update I got I ロスト all my apps ,because あなた need a lot of storage 宇宙 for it.

In rare cases,it tells あなた that あなた need to 削除 so much data ,but not always.

If あなた have lots of apps and like it how it is I wouldn't risk it.

Anyway if あなた are unsure about how it looks ,then this how it looks.