I installed it this weekend. After initial frustrations of not being able to find anything where it was supposed to be, I got used to the new way of doing things. Now, a few days later, I actually like how it is being done now. The Start Screen is more like a gigantic Start button. You have to organize it to the way you want it to work, move, delete and add tiles the way you want it and the new UI starts to make sense. The metro (or "modern UI") apps are full screen when opened and are extremely fast in their UI. The tradtional apps open on the desktop = just the way you are used to and all have the traditional UI, 

It takes a day to get used to it, but after that it becomes intuitive and you don't miss the start button anymore