You had about 20 items to choose (up from 4), from which 9 you could access using a simple key combo. It was amazing! I saved several minutes of my day that were wasted searching for files in very deep folder trees. Moreover, that was a very nice pin feature, that allowed you to hold or pin down a certain file to that list. This made sure that the file would remain in the list even if you don't access it very frequently. In short, it was a Favorite File combined with File History.
The recent file list as of Office 2007 (picture taken from here)
And what I loved the most was the fact that I could get some files very quickly. Inside Word, for example, I'd type ALT-F, 1, and wow! That timesheet that I used everyday would be open. The great advantage of not having to search is that I didn't had to focus my mind in opening the file: it was a mechanical task. Looking for files in directories requires focus because you have to scan the folder for your file.
The problem is that, in Office 2010, which I have been using for some weeks now, the Recent list is not on the "File" menu, but on a sublevel of it. If, having something open on Word, I go ALT-F, I get:
Some names where censored on purpose
To access the Recent files list, I have to click at the Recent item on the left-side menu! Or the other hand, the features that I'm seeing here aren't really that useful. In fact, I don't recall ever using them on Word 2007. So, another tip for MS Information Architects: Verify which features are mostly used and make them more easy (direct) to access.