The other half aren't negative per-se, but they don't seem to care as much (view it as just a job). Or one guy moved to Haskell and then sorta looked down on F#. There's also some frustration sometimes when something hasn't clicked and "should" be easy. Often this is because F# is taught at a high level, without showing the simple primitives that built it up from scratch.
The non-programmers are less positive. From them, I hear "Yeah but it's so concise no one can understand it"[1]. I once got a "If we use F#, then when we exit for (huge figure) we might get less money.[2] Or the general "but this isn't mainstream" (MS's fault for shitty F# marketing.)
And there's also the "ok but we can't find hires". Which is the second worst one. Because on anything that's not some boring CRUD like app, the work to learn the domain and everything about the app dwarfs learning a new language.
(The worst excuse is the nonsense "best tool for the job" as if F# didn't out-class C# in essentially every single aspect. I find this excuse is pulled out a lot, as a way to handwave away real criticism or discussion.)
1: This is just unfamiliarity. In general, less code = less bugs, less work to understand.
2: True if you're selling a business that's a simple website. Not true if you're selling a business that revolves around all your code does.