I have installed IE 9 and I made the following observations so far:

1. The speed is, well, extremely fast as oppose to previous versions.
2. When we open a new window, it doesn't take some time as previous versions and acts as if we are simply navigating into another page from the same window.
3. It allows a wider vertical area as everything has been optimized as the top so we probably get at least 40 pixels more in the height.