Google has recently been rolling changes in all its service Including Google search , Google news, The new elegant catch the eye of everyone. Google is rolling the new design to its all services. You can simply get the new design for your Gmail by choosing the new design theme.
The previous design was working fine for me. But after rolling out to the new design view I was astound by the clean amazing look I got. See the below screen shot to find the differences between the Classic and the new design.
You can activate new interface by Clicking Setting>>Theme>>Preview Theme. The new design in more cleaner and elegant than the previous one. Google is rolling its new design to all its service. Soon it will be the default layout for your Gmail. Till then you can use the preview theme for enable this layout. Morever Google has launch few more stuff in its Google lab like preview pane features make it more outstanding like other email provider in terms of design.