Rabbinic tradition is rather ambivalent about him. Whilst he was a mercenary prepared, after fitting expressions of initial reluctance, to be hired to curse Israel, he did find himself unable to say anything negative, and his words of praise – Mah tovu ohalecha Yaakov, “How goodly are your tents, O Jacob” (Num. 24:5) have entered the Jewish prayer book.
Yet the sages called him Bilam HaRasha, “Bilam the wicked”, and thought he and his followers were not entirely moral or ethical (Ber. 7a, Avot 5:21, etc.).
They made the homiletical suggestion that his name indicates b’lo am, “without people”, i.e. that he would not join the heavenly community in the World to Come (Sanh. 106b).
The disciples of Bilam would also inherit Gehinnom because of their “evil eye, ambitious soul and haughty spirit” (Avot 5:21).