To me U/X consists of many things – design/look-and-feel, navigation, content, information architecture, etc. Certainly it would help if you have design skills and HTML experience but you need to understand from a user’s perspective how they interact with the app and their needs. U/X is the overall experience that an user has while interacting with an app. It is not just one thing that will make the user experience great but rather the total of many different components.

For instance, if the navigation is really well thought out but the content is not that relevant when they get to a page, then the U/X is poor.