There isn't much bad to write about Ballon. I don't know what people could dislike about this movie. To me it was entertaining, with quite a lot of suspense once you're into the story, a good cast (even the kids), and it's all nicely shot. I understand everybody was suspicious of the Stasi at that time, your best friend could betray you, but in this case I think they exaggerated a bit in order to make it more suspensful. But the suspense was the good thing about the story, plus the fact that it's based on a true story which made it even more appealing. It's one of the better German movies I've seen lately, certainly worth a watch if you like escape movies.
Review of Balloon
