Recessed medicine cabinets make great use of space.  The correct placement and make them even more useful.  If you prefer a deep cabinet capable of more storage, like this client, installing it in the wall above above the vanity may not be the best location.  Trying to use the mirror and constantly opening the door to get things can become annoying very fast, especially if there is more than one person involved.  Installing the cabinet on the side wall eliminates that problem.  It also frees up the wall above the vanity, allowing you to put in a full width mirror.