Late last month I conducted a short experiment into the usability of Microsoft's latest productivity suite, Office 2007. I gave the software to a typical, clueless newbie who had never used the software or its ribbon interface before: ie, me.

My first impression was that the ribbon can be bewildering and confusing to those schooled in expanding menu trees. My second impression was that organisations deploying Office 2007 will need to do what most don't: spend some time and money on training.

I'd never felt much dissatisfaction with the old menus, so it seemed to me that Microsoft had indulged in a spot of fixing the unbroken. What were the firm's user-interface experts thinking when they dumped the more familiar structure?

Answers can be found in one of Microsoft's many official blogs – specifically the work of Jensen Harris, group program manager of the Office User Experience Team. He has written an eight-part explanation, entitled The Why of the New UI, in which he reveals much intriguing information.

For example, the most-used commands in Word 2003 are: Paste; Save; Copy; Undo; and Bold. These five commands account for around a third of all the commands issued by users. More surprising than the fact that Undo is not number one is the knowledge that Microsoft has these figures at all. They come, of course, from the optional feedback agents in its software. Equally illuminating is a graph of top-level menu items in successive versions of Word (50 commands in Word 1.0; something like 270 in Word 2003).

So the revolution in organising and presenting Office's functions was sparked by a study of real user habits, and the knowledge that Word has become too bloated for menus to work properly.

I should backtrack for a second. What Harris actually says is that necessary complexity has been mistaken for bloat: "The industry press started publishing articles and popularising the idea that Office was 'bloated'. In reality, the programs themselves weren't bloated," he argues, citing long lists of feature-requests that suggest "people expected us to do more".

I think Office is bloated. It's a general-purpose package carrying the baggage of countless specialist tasks. I suspect better on-demand incremental installation might have been preferable to a new UI.

All this aside, there are some startling admissions in Harris's blog. The adaptive menus prevalent in Windows XP, which were trumpeted as a wonderful way of dealing with complexity, "were not successful" and have been dropped. Harris defends the decision to create them, arguing, "We're analysing this with 20/20 hindsight."

I can't help wondering what the wisdom of hindsight will do for the tricky new ribbon.