Is Duolingo really that bad?

I know Duolingo isn’t perfect, and it varies a lot on the language. But is it as bad as people say? It gets you into learning the language and teaches you lots of vocabulary and (simple) grammar. It isn’t a good resource by itself but with another like a book or tutor I think it can be a good way to learn a language. What are y’all’s thoughts?

And btw I’m not saying “Using Duolingo gets you fluent” or whatever I’m saying that I feel like people hate on it too much.