I have been working with the Office 2010 Beta for about a week now. I downloaded the Professional Plus version on January 17 and installed on my test PC which is an old Pentium III with 512 RAM running Windows Server 2003. The install was quite similar to the Office 2007 install.
The program launches faster than 2007. Gone is the Office Button, in favor of a File tab on the ribbon which brings up the Backstage area which has basically the same content as the button. For the beta there are two smiley icons in the system tray, Send a Smile and Send a Frown (I am not kidding) for feedback to Microsoft.
My first real test today was with Access 2010, using a time & billing program that I use for consulting work. The front-end is Access 2000 format, and the back-end is Access 97. I run the app using Access 2003.
When I first opened the file, even while holding the Shift key, I got an error message
The command or action '' isn't available now.
I went back to 2003 and decompiled the app & then compiled & saved, since this is oftentimes a quick fix for unexplained errors; that did not help. The app has an AutoExec macro that opens a form and then maximizes the window; once the file is open, I can run the macro, or open the form, without any error message. Obviously Access 2010 is doing something I don't know about. I visited the Trust Center & enabled the macros, and also set the ActiveX to be wide open but the error message still shows upon opening the file. This test PC does not have any anti-virus software installed, so that is not a factor either.
The app has a popup form with a Calendar 2.0 control, but alas 2010 does not support it. Whilst browsing the dev info for hints, I noted that data access pages (DAP's) are on the way out - never used them myself - 2010 does not support creation but apparently still runs them.
There are a couple of other things that don't seem right. When you have the Navigation Pane open and the ribbon is at the Home tab, you can select a form or report & the Design button shows, but it does not show for the other objects tables queries etc. But you can right-click on the object to get into design view.
Also, if the ribbon is minimized & you preview a maximized report, there is no close button or "x" so you need to either right-click and Close, or press Ctrl-F4 which still works. You can add the "Close Preview" button to the Quick Access Toolbar, but it takes 2 clicks to close the report - 1st click shows a red Close Preview button, you have to click that to close the report.
Otherwise the app seems to work OK. Next I will try some design changes & see how that all shakes out. . .