To the start of the page you will see a reasonable layout. Notice that you can use the ThemeRoller to create style sheets interactively and then load them into your page to customize the way things look. All you have to do is select the styles you want to apply and a style sheet is generated.
For example, notice how the data grid is fully interactive and allows the user to edit the data and how it can present multiple pages. Using jQuery's Ajax method it is fairly easy to send and receive JSON-formatted data.
Now you know how the basics work you can explore the other controls, The basic controls include:
Grid with Selection, Sorting, Filtering, and Paging
All the controls are touch enabled and a layout manager can be used to provide responsive layouts that should work well on any size of device.
In addition there are also some frameworks that enable you to organize larger parts of you application. The Word, Excel and Documents engines only wok in ASP.NET but give you the ability to give the user complete document processing facilities. The templating engine lets you build grids and tree menus. There is a data source which can handle data from oData, WCF, RESTful Domain Data Sources, JSON, XML, local arrays and static HTML tables.
Of course, in addition to all of this, there is a complete set of controls that work with jQuery Mobile. jQuery Mobile has some basic controls but Ignite UI extends these to the sort of sophisticated controls that make creating apps easier - ListView, Pivot Grid, NavBar and so on.