Albert Barnes Commentary 2 Kings 23:22

"Surely there was not kept such a passover from the days of the judges that judged Israel, nor in all the days of the kings of Israel, nor of the kings of Judah;" — 2 Kings 23:22 (ASV)

The details of the Passover are given by the author of Chronicles (the marginal reference). Its superiority to other Passovers seems to have consisted in the following:

1. The multitudes that attended it.
2. The completeness with which all the directions of the Law were observed in the celebration.

Compare this to Nehemiah 8:17.