Either you do a window-based DE or an application based, Gnome 3 went for application based. I happen to like it, a lot. this includes alt-tab behavior. If you happen do not like application based, then you should probably not try to turn Gnome 3 into one, there are other choices for you.
I think Gnome 3 is the best thing that happened to the *nix desktop for a long time. The navigation is fast if you know how to use it. I do use a few extensions, like static workspaces (altough I think this is included in 3.4). It also happen to be quite fast, running it on my ion2 netbook, no problem. Have never used a composition desktop before, they where all to slow. Gnome 3 changed that.
Gnome developers have always had cojones and done things which may not look to be the right thing, in the end they come out winning, this time should not be an exception.