Seriously, in reality, gnome3 and gnome shell are pretty nice.
[and I have exactly the feeling you do: it gets out of my way except when I want to use it, and then it's easily available]
The gnome shell especially is also a welcome sign that there's some independent thinking about UIs going on, which is a welcome change from the painful old "let's be just like windows with a few tweaks!" schtick of times past.
Its worst sin is that it represents change, and, well, people hate change... :[