I've been really enjoying Word and Excel 2007. They work as expected and I actually prefer the new "ribbon" to the old toolbars and menus. I even know where to find most of the functions :-)
However, the Outlook 2007 interface is a little "inconsistent" (the program itself is fine). First, a quick screenshot:

Here are my five gripes on the Outlook 2007 interface:
- Outlook should use the "ribbon" interface. I like the "ribbon". Word uses it. Excel uses it. Why can't Outlook?
- The double-chevron above the To-Do bar expands the To-Do bar, and "pins" it. However, only the double-chevron is selectable which presents a very small target. A better way to do this would have been to remove the double-chevron and use a Visual Studio-esque "pin" icon to keep the To-Do bar open.
- The scrollbar for the meeting request heading is not themed. The scrollbar for the meeting request content *is* themed. I have themes turned off (but Office 2007 still uses it's own visual style). This should be consistent.
- The meeting request buttons are not standard. They should be either a toolbar button or a normal button, but not a different style from every other button.
- There's no mouse-over effects on column headers. I don't know if this is because I have visual styles turned off or not. It's just there's an orange mouse-over effect on just about everything else (except the blue for scrollbars, and silver for some other things) and I reckon column headers deserve a mouse-over effect.
Here's some of the things I *do* like about the new Outlook interface:
- The entire To-Do bar on the right hand of the screen is clickable. A click expands it, and mousing away from it retracts it. This is good because the feature is easily discoverable, and repeatable with no side effects.
- The To-Do bar is really helpful. Two thumbs up.
- The Calendar has been improved, adding links to previous and next appointment when you're in "Day" view. This makes it easier to navigate your way around appointments.
Tags: outlook, user interface, office, ribbon