My preferences on how to use $resource.

AngularJS $resource usage

/*
 * HTTP GET actions: Resource.action([parameters], [success], [error])
 * non-GET actions: Resource.action([parameters], postData, [success], [error])
 * 
 * From AngularJS doc: http://docs.angularjs.org/api/ngResource.$resource
 */

/*
 * Direct assignment
 * This works, but during the call it sets variable to object input to $resource
 *     which might be a side-effect that you don't want.
 */
$scope.registerResult = Login.update(registerInput);

/*
 * On-success assignment
 * Sets variable to response body/object, only if successful
 */
Login.update(registerInput, function success(response) {
	log('success response: ' + angular.toJson(response));
	$scope.registerResult = response;
});

/*
 * On-success plus on-error
 */
Login.update(registerInput, function success(response) {
	log('success response: ' + angular.toJson(response));
	$scope.registerResult = response;
}, function error(response) {
	log('error response: ' + angular.toJson(response));
});