[rnd me]

@ is a syntax error...

well, you also re-define the function toggleIsFollowing() as false, probably not what you want to do.


if that's not it, it sound like the this/that thing we usually see in dom events.
why not just close it instead of going through knockout?

 function AppViewModel() {
       var toggled = true;
        this.toggleIsFollowing = function () {
           toggled  = !toggled 
        };

        this.isFollowing = @Model.IsFollowing.ToString().ToLower()
        this.followButtonText = ko.computed(function () {
            return toggled  ? "Follow" : "Unfollow";
        });
    }