I just installed the v2 IDE and it is a very nice improvement. However a feature I was hoping for is (still) missing: the ability to see all your sketches in the UI. Like the web-based IDE, I want to be able to see my sketches in the left panel so I can easily click through them. I get that you are binding a window to a sketch but I should be able to more easily see what I have, and open files in tabs (ideally).
And as far as multiple windows goes, if that is your model, you must have a "Windows" menu, or a gadget on the left, to allow me to easily flip between open sketches.