I'm a proponent of the Ribbon UI and I fucking hate toolbars in OS X.
I use Outlook, Word, Excel and Windows Live Mail extensively. All of which have the ribbon UI. It turns out that for the sake of actually getting stuff done, this is incredibly useful. I genuiely hardly ever need to use the context menu because what I need is there "in my face" and "obvious". While this fits newbie usage patterns perfectly, it also helps us power users who don't always switch back to the keyboard shortcuts (mouse already in hand) and don't want to jump through several hoops (like faffing with context menus) to get stuff done.
On the other hand, I have absolutely no fucking idea what the hell the toolbar buttons do when I'm using Finder or Mail on OS-X (Snow Leopard and Lion). The icons are crap, there are no visual cues and I always end up dropping to a terminal to get stuff done because I simply can't be arsed to figure it out or piss around with right clicking or the awful keyboard shortcut system on OS X. I don't think people usually get that far with OS X without getting "shiny I paid $2000 so it must be good Apple mental block" as I call it.
I'm fed up of so-called self-proclaimed experts chucking out blog posts criticising user interfaces while masturbating over Apple's efforts. Microsoft's UI allows you to get shit done and get it done quickly. So it might not be as aesthetically pleasing, but it works and works well for those of us with shit in our eyes.
Also, Microsoft research what you want rather than tell you what you're having (like Apple do).