On the one hand, I understand that people enjoy with that because you can go and have fun with your friends. Besides, people go there not only to drink and it is cheaper that going to any pubs or discos.
On the other hand, the botellon give young people the opportunity to start drinking when they are still too young. Besides, in that place you can get all types of drugs and, in my opinion it should be more controlled by the police. Finally, it should be taken into account the amount of rubbish that each party produce.