I find the optional parentheses, and the way that keyword lists are defined to be the two biggest stumbling blocks when I come back to Elixir after a while way.

Coming from other languages, I find that

    example("with", 3, extra: "arguments", as: "a", keyword: "list")

being equivalent to

    example("with", 3, [extra: "arguments", as: "a", keyword: "list"])

and

    example "with", 3, extra: "arguments", as: "a", keyword: "list"

always takes some extra mental effort to get through, especially when there's no parenthesis. But I appreciate not having to write all the extra brackets and parens when I get going, so I think it's a fair tradeoff.