I have no particular problem with Gnome Shell, except that like Unity it is unusable when you have lots of windows open. I always have many terminals, editors, browsers etc open (across two large screens) and a taskbar like interface has been by far the least worst way of dealing with those. Gnome 3 has sporadically had a taskbar as an extension but by design they break on every Gnome update, or they are missing functionality (eg drag and drop reordering of icons).