Office 2007 is a nightmare at first because of the totally redesigned Ribbon Interface. However once you get used to it, it is really is very good.
You can ease yourself into the learning curve by installing the Classic Office Menu plugin. It adds anoother tab to the ribbon that provides the original 2003 style menus and toolbars.
http://www.addintools.com
However if you computer is quite old you might have trouble. I assume it uses more memory and cpu power than earlier versions.
Formattng in Word 2007 is significantly improved. The formatting is applied to the document while you hover over the settings so you can see what it will look like before you select it.
Excel 2007 can handle more rows and columns then you could ever imagine using. Previously Excel was limited to 256 columns and 65536 rows.
Improvements in Access 2007 are awesome for serious database users. I would never go back now.
With PowerPoint beware. Saving presentations in compatibility mode is supposed to allow them to work in Powerpoint 2003 (XP). There can be problems with PP2000. If you give them to others to present also provide them with the free Powerpoint 2007 viewer available at the Microsoft site.
All previous versions of Office documents open in 2007.
And lastly there is the excellent save as pdf plugin which you can download from the Microsoft website for free.