The ease at which you can navigate through your account once logged into it! You don't have 10 different accounts open if one isn't working for some reason or another (such as payment issues).
I've had very few problems since we started using this system - usually just minor glitches when troubleshooting something specific but nothing too serious so far either way.* Easy navigation between orders/accounts* Great customer service from both staff members who work there AND those within 3rd party companies such as UPS & FedEx.