I've been using GNOME 3 for a few months, and I actually am on board with this decision; it feels better, and looks fine. It takes some getting used to, but a button press (win key) or mouse flick is a lot faster than "mouse mouse to the corner, position it over the start button, click".
Does make me wonder how it'll work in multi-monitor setups, though. Presumably you can change the hot corner, but if that's not a launch feature there are going to be some severely annoyed users.