In Israel, reactions were united. Begin was a hero. He ended decades of war, and received recognition from an Arab country. Only a few settlers in Sinai opposed the Accords. They tried stopping the government from removing their settlements, but were unsuccessful. Most Israelis were happy: a poll taken in 2001 by the Jaffee Center for Strategic Studies showed that 85% of Israelis were in support of the Accords.
Americans had many different reactions. Many people were against the Accords because it neglected the Palestinians. There were protests against the Accords, in favor of Palestine. Other people supported the Accords.
The USSR was against the Accords. They supported the Palestinians and Arabs. The Soviet government released a statement condemning the Accords. The Soviet reaction could've been because of Sadat cutting off relations before the Accords, or because of their general hatred towards the west.