The ability to create customized pages quickly, with different layouts for each page. It's very flexible because it offers many possibilities in combination of themes/templates that can be used depending upon your need and requirement at any given point of time. I think customization options could have been better as there are no predefined templates available which might not suit everyone or every project situation. However this has nothing much if anything do about functionality offered by other competitors like wordpress etc. Highly recommended! We use gupypcms mainly due to its flexibility & ease. This enabled us to implement certain features quicker than we would otherwise have done using Word Press itself.