It has lots of animations and other stuffs which had attracted the users to test Windows Vista but don’t know why Microsoft has changed their mind and we had got something new in final build.
Anyways if you too had liked th interface of Longhorn then here is the Longhorn Skin Pack created by hameddanger at DA.
This skin pack provide new Boot Scree, Logon Screen, Themes, Wallpapers, Icons and lot more which allows you to get Longhorn feel in your Windows 7 machine.
You can install it on Windows 7, with or without SP1 on both 32 Bit or 64 Bit.
P.S.Make a system restore point before installing this skin pack, if anything went out of plan then you can easily switch to stable stage.