EF is good for setting up seat alerts to get a desired seat in E+ especially if E+ is full when you book or if you are Silver. Many times my spouse or I have been able to get out of a middle seat or go from E- to E+ in the hours before a flight because of the alerts, which are free for windows/aisles but not if you want to pick specific seats or sections (e.g. E+ only). It saves you from compulsively having to check the seat map on the app. Also, EF can show you which seats are being blocked.