I must also be the one of the very few members of this site that generally likes the Ribbon UI. When it first came out for Office 2007, the first thing I did was install classic menu UI AFTER installing office 2007 (before updating it even) becase I too hated the sudden change without any built-in alternative. But after working with it for a few months it grew on me, with me now being "fluent" in both UI, sometimes faster with the ribbon. Granted, I use keyboard shortcuts A LOT, so I don't necessarily find myself going to the top interface for most of my actions. When I do and it's a common feature I've either pinned or is by default showing, I find the Ribbon UI much faster.
So I welcome the change with open arms, though I do hope there will be the option for the classic menu UI, just in case. I still have to get used to the new File tab and other small changes they introduced in office 2010... which is difficult since none of my own personal or work computers have it (a couple friends/family do though).
@using too much space: well, when I'm looking at/editing a long portrait document that I'll be with for a while, I simply pivot my screen or turn my laptop on it's side, so I don't get the concern. /troll
Seriously though, I SUPPOSE I understand for laptop users and the lack of vertical space; you can blame manufacturers for not using or offering 16X10 screens (1920x1200 for instance). =p The option to be able to dock the ribbon on the left or right sides would be nice, sorta like how image editors have the floating vertical toolbar. Might be more difficult for regular users but that's why it would be an optional location.
About regular users vs power users: Those of us who would mark ourselves as power users are in what I'd call the loud minority. We'll complain, but in reality the majority of users which Microsoft caters to are just "regular" or "light" users, which they,in my experience [with dealing non-power users], generally profit from the more visual and "space wasting" Ribbon UI, opposed to having to dig through a menu, even when they are familiar with it.
Just my thoughts.