There are a lot of reasons as to why I find this picture beautiful, I think it carries a big message and makes you think about what is happening behind this picture. Theres obvious contrast between the black riot gear of the police and the white heart shaped balloon, which is one of the main reasons its a beautiful picture but there are also some gestalt principles in play here, the law of similarity and the law of proximity are in play here with the riot police, we obviously know they are all together as a group and assume that some opposition is also there or else they wouldn't be.
Context also plays an important role in this photo, without context we can come up with all sorts of ideas to the story behind this photo but when context is added it gives it a whole different meaning. This photo was taken after a small child at a protest in Romania made it and gave it to the riot officer, the fact that the officer kept almost communicates that he doesn't necessarily agree with what the Government is doing but he has a job he has to perform.