Yeah, I looked it up and gave a link to wikipedia here, already. I was not sure, cause the last time I read something about him was like 10 years, ago. You have to read the exchange between Marx and Engels, you'll find more there. It's obvious that nobody would remember Stirner, if Marx & Engels hadn't critized his ideas.

[–] [email protected] 3 points 1 year ago

The edition I read has a commentary at the end that talks about various people's opinions of the book in the years following its publication, and quotes some passages from Marx and Engels' letters.

It's amazing how few people have maintained a positive opinion about him/his work for more than a few years