This post hits close to home...
A year or so ago (pre-Unity), I decided to try an experiment around the office. We had some desktop users who were claiming to need a notebook for things (travel, presentations, etc...). We have tons of old notebooks that we cannot donate or trash yet due to the specifics of the funding they were purchased with. I took a couple of the old notebooks and prepped them with Ubuntu then themed it to resemble Windows (was not going for a 100% duplication). "My Computer", "My Documents", etc... Put appropriate shortcuts on the desktop and handed it over to a couple of users to try out. Now keep in mind the office had not yet switched to Windows 7. With the exception of the IT group the rest of the office was XP.
Fast forward a couple of weeks and I had scheduled a "check up" to see how things were going. I was getting worried because I had not heard anything out of most of them. My guess was they freaked out and just did not use the notebooks.
Instead I found out that they really like their "new, fast computers". They especially liked the non-Ribbon interface of Open Office over what they had seen from Office 2010.
Now a few things to point out... These were typical “worker drone” users here. No special software like AutoCad, Photoshop, etc is needed in their daily work. Give them a web browser and “Office” and they have what they need. I did have a problem getting the notebooks to print to a networked Ricoh copier/scanner/kitchensink device, but the Ricoh was brand new at the time so that might not be an issue if it was a little older.
All in all the experiment worked out much better than I expected. All except one of the users wanted to keep their notebooks around, so since they were working ok we let them until it came time for us to change out the dept’s computers to Win 7. When we changed over, they received notebooks with docking stations instead of desktops so there was no need for the linux notebooks.
This might be an anomaly instead of the rule, but considering the target users, it all worked out better than I expected. I have not tried a similar experiment since Unity came around. I think that would cause a much more "alien" feel to it than the older version of Ubuntu did. Not that users can't get used to it, but if one of the goals is to minimize distraction and alienation, then I don't think Unity will help matters much.