GMail has revamped its new look along with new features making it more intuitive and fast. This new look gives a feeling of using email client application once you login to GMail.
New features available with the new look are
Streamlined conversation: Now its pretty easy to read and keep track of email conversations from friends, family and colleagues through streamlined conversation threas
Elastic density: The GMail theme can be adjusted according to the screen sizes
New HD themes: Now you can have HD quality images in GMail themes
Better search: is is one is the feature I liked very much. The input mechanism has been improved to accept parameters and queries through a dialogue box.
You can switch to the new look in GMail by clicking the link at bottom right corner.