Edit in JSFiddle

angular.module('myApp', [])
    .service('Session', function () {
    // built on login, contains information about the current user

    var user = {
        firstName: 'Alec',
        lastName: 'LaLonde',
        active: true,
        joinDate: new Date(1444166612822),
        roles: [{
            name: 'Administrator',
            isAdmin: true
        }, {
            name: 'Owner',
        }]
    };
    return user;
})
    .service('UserModel', function () {
    function UserModel(user) {
        angular.extend(this, user);

        this.isAdmin = this.calculateIsAdmin();
        // this could be a filter also
        this.fullName = user.firstName + " " + user.lastName;
    }

    angular.extend(UserModel.prototype, {
        calculateIsAdmin: function () {
            if (!this.roles) return false;
            return _.some(this.roles, 'isAdmin');
        }
    });

    return UserModel;
})
    .controller('MyCtrl', function ($scope, Session, UserModel) {
    $scope.userModel = new UserModel(Session);
});

<div ng-controller="MyCtrl">
    <div class="panel panel-default">
        <div class="panel-heading">
             <h3 class="panel-title">
                 {{ userModel.fullName }}
                 <span ng-if="userModel.isAdmin" class="small pull-right badge">Administrator</span>
            </h3>

        </div>
        <div class="panel-body">
            <div class="row">
                <div class="col-xs-4">Active?</div>
                <div class="col-xs-8" ng-bind="userModel.active"></div>
            </div>
            <div class="row">
                <div class="col-xs-4">Joined on</div>
                <div class="col-xs-8">{{ userModel.joinDate | date:'short' }}</div>
            </div>
        </div>
    </div>
</div>

body {
    margin: 15px;
}