Should I use is_admin() inside ‘admin_init’ hook callback

I’m adding an action witht he following line:

add_action( 'admin_init', 'fb_init_scripts');

And my function looks like this:

  function fb_init_scripts() {
    //Only use these scripts in admin interface
    if (is_admin() ) {
        wp_enqueue_script('jquery-ui','http://ajax.googleapis.com/ajax/libs/jqueryui/1.7/jquery-ui.min.js',array('jquery'));
    }
  }

In this instance, is it pointless to use is_admin() to controll if I’m in admin panel, since I’m running this function in admin_init ?

Yep, pointless.

admin_init only fires in admin area (and couple more files related to AJAX functionality) so additional is_admin() check is not necessary.

It often comes up in examples for hooks that fire both on front-end and admin area.