According to the leaked information ,On terms of discussion IE 9 has been divided into 4 parts :
- Performance
- GPU-Powered HTML 5
- Standards – Same Markup
- User Experience
1. Performance of IE9 is expected to be magical since it have new javascript engine ,integration with DOM elements ,layout optimisation.Here is the rating 
2.GPU powered -HTML 5
3.Standards – Same Markup
4.User experience
They have been monitoring about the add-on feature.
The leaked also gave and idea that IE9 beta will be out by August 2010 and that will be first release of IE with full functionality. How does it sounds?? Looks nice to me.