My comment is not intended to be for or against this law, I just want to explain what an "ordonnace pénale" ("penal order" in english) is.
It is a procedure that already exists in France. It is not being introduced by this law. It allows the prosecutor to notify you by letter of a proposed sentence (monetary, general interest work, compulsory treatment, but not jail time). You can either accept the sentence or reject it and go to court where the prosecutor will again suggest the sentence but a judge will decide.
It is inspired by the "plead guilty" procedure in the US with the notable difference that it is strictly limited to minor offeces. There is no way to handle a murder case through a penal order in France.
This simplified procedure was put in place to save time and it does save a lot of time and money to the juducuary administration indeed.