That's fine; I don't have an issue.
1. The software release was very buggy (understandable) and slow.
2. Nothing exceptionally different. Not the features I was looking for.
I have been using it exclusively since GM1.
I found GM1 crashed a few times. More than I would have expected.
GM2 seems more stable.
Not had any performance issues at all. Compilation seems virtually instantaneous.
I find my productivity has improved over XCode3.
The workflow makes more sense to me. As if someone has actually designed it, rather than left it to a bunch of engineers.
I found I drowned under a heap of windows in 3. In 4, the multi-pane editor helps makes it easy to keep the stuff I am working on - visible without clutter.
The inline syntax checking is effectively running a compile in the background, so I don't have to press build to see syntax errors.
The smart editing suggestions speed up code entry. I like how code warnings are slightly more annoying, which encourages me to tidy-up.
The tabbed navigation sidebar is a really fast way to find stuff.
In short it just makes more sense.
Obviously you don't need *any* of this stuff. But for me, it saves time.
C.