1) Function signatures do not read in the same way as most other languages. This "muscle memory" is a barrier to unlearn when moving to Go, and I don't see any good reason for it other than "being different".

2) No try/catch. Inexcusable in my opinion.

3) The syntax for declaring maps/arrays looks gross. Again, being different for the sake of it.

4) No while loops. The for loop syntax is not too bad, but I think this was again a choice made out of trying to simplify things when not a single person ever complained that "Java/C has too many types of loops".

I could go on, but in general my opinion is that Go deviated from some good established norms for no good reason, and this makes it much harder to adopt. It also isn't fun when you have a code base with e.g. Go and Java or Go and C# mixed in. The mental overhead of having an entirely different syntax to reason about is frustrating. And for what benefit? At least list comprehensions in Python are nice to read. I can't think of anything that is nice to read in Go.