There is a nice blog post about the UI changes from Blender 2.4x to the 2.5 series. All in all I think the new UI is much improved. However some things are still not perfect. e.g. Blender windows on OS X are not resizable, apart from the zoom (+) button. That’s because the resize corner in the lower right is missing. On Linux, this will be provided by the window manager. Anyway, here is an idea of what Blender 2.5 looks like:
