Everything is broken. I would say unbelievable but we're used to this so this is just to warn everyone.
Examples include:
No horizontal scroll bar in the text editor so you must use the keyboard (this is actually funny)
Xaml previewer no longer works
Intellisense is no longer working (apparantly it works if you open all your files in the editor)
Go to declaration no longer working
Go to implementation no longer works
Considering the previous version was so good this is a real disappointment. This version uses an entirely new editor but it seems it hasn't been tested all that well.