More nitpicking…

> +            (uri (string-append
> +                  "mirror://sourceforge/htop/"
> +                  version "/htop-" version ".tar.gz"))

Could you place ‘string-append’ and "mirror://sourceforge/htop/" on
the same line?

> +   (arguments '(#:tests? #f))

Why did you disable tests?  Could you add a comment about that?