In my experience, Algebraic types alone take some work to get used to using competently. That's just one F# uniqueness and there are others. Learning Elm (a similar language) definitely made me a better engineer, but I really don't think learning F# is the same as learning Python for someone with experience with imperative/OO languages.

I think the reason it sometimes seems like it is that easy is that, as we gain experience with tools, we tend to forget the difficulties we had learning them.