Rabbi Yoel of Satmar said: “It is worth it for a person to live 70 years and to suffer trials and tribulations just to hear the Megillah reading once!” Why is this so what is so special about the reading the Megillah?
1. The Darkei Moshe explains that during the reading of Megilla the original outpouring of G-d’s compassion on us at the time of the miracle of Purim pours out again on us every year. Therefore when we read the verse “The Jews had light and happiness and gladness and preciousness,” those things get poured onto the nation of Israel anew.
2. This is the reason why after reading the Megillah we say Kaddish with the prayer of “Titkabel”- that God should accept our prayer. Because the Megillah reading is really one big prayer and supplication for G-d’s help that is hidden between the words of the Megillah. When we say the Kaddish we're asking God to accept the requests hidden in the Megillah.
3. Rabbi Levy Yitzchak of Berditchev writes wonderful things about the time of reading the Megillah: “From now on a person should be very excited when he reads the Megillah and should concentrate on the thought that from now on he will accept upon himself his Torah and his mitzvoth. He should prepare himself thinking that whatever passed is already gone and from now on I will accept upon myself my Torah and mitzvoth.
Rabbi Levi Yitzchak adds and explains that “Purim is like Yom Kippur. God forgives and cleanses Israel of all their sins. Because of this a person should regret his past sins and accept to do good in the future. When a person hears the reading of the Megillah G-d pours on him purity at that time and this is the proper time to make a clear decision to avoid sin.
4. “At the time of reading the Megillah a great material abundance is poured down on the person and a person could merit the abundance of children, life, health and livelihood.” (Tiferet Shlomo)
5. In addition, at the time of reading the Megilla G-d forgives our sins even the serious sins. The Shearit Yisrael points out that even the most serious sins, even forbidden relations can get cleansed.