According to the Dropbox Blog, the new website will focus on simplicity and usability. It introduces an "action bar" along the top of the screen that offers contextual options for files and folders alike. The same commands will also be available by right-clicking as always.
Dropbox has also improved its photo viewer to allow full-screen viewing and now displays video and image thumbs. The biggest change has got to be the demise of the old UI's ubiquitous selection check boxes. They've been replaced with much more intuitive drag-and-drop mechanism. [Dropbox Blog]