I feel that is no longer a valid excuse. I use ubuntu on thinkpads, and it just works.
I see people around me with more issues with their OS X machines in fact. That might be just anecdotal, of course.
You caught Ubuntu (or Fedora or other distributions that moved to GNOME 3) were on GNOME 2 greater part of the last decade. A breaking UI change had to be done at some point, and it happened to be 2 years ago. Even on macs, there was a huge overhaul going from OS9 to OSX in 2001.
You can make a point saying that you don't like the new UI. That will be a much more sound argument than saying the environment is changing from one release to the next.
My mother started off on 8.04 LTS. When upgrading to 10.04 LTS the window buttons changed sides and there was a new theme (this is enough to throw many users). When upgrading to 12.04 LTS there was a change from Gnome to Unity.
My mother now chooses to use a Mac because she was fed up with her computer "changing" each time I updated it. I doubt I could convince her to try any Linux distribution again - there are no perceivable benefits for her.
Edited to add: Not that I think Window Maker is necessarily the solution. I'm just pointing out that the default Ubuntu repos contain a huge number of window managers and even a few desktop environments which haven't changed that much between releases.
What sort of battery life do you get? Any heat issues? Hibernate/suspend?
(These are all areas where I've had issues with recent versions of Ubuntu, but on an older model Macbook Pro rather than a Thinkpad)
Using openSUSE 12.3 with 3.7.11+ kernel on a Thinkpad T530 (Intel graphics, 9 cell battery) I get 4-12 hours of battery life (depends on usage; coding and work on a dimmer brightness gets me 10-12 hours, watching movies and playing games with the brightness higher up gets me ~4-5 hours).
Newer kernels seem to have regressed as far as power consumption goes, I was trying the 3.10 kernel and getting 2-3 hours of battery life...
Really, at least with thinkpads, the just works excuse is just that: an excuse.
Looking forward to my X1 Carbon, already in the mail :-)
No heat issues.
Suspend works perfectly. Takes a few seconds to unsuspend, but that's about it.
Macbooks are much worse supported than thinkpads. For all purposes, thinkpads are the reference platform for linux, like macbooks are for OS X.
I say this as a 17 year linux only user. I am not trying to disparage linux, I just want to point out that the thinkpad is an exceptional case.
When a reasonably prudent consumer hears "OSX runs great on my macbook" they do not come away thinking that OSX will run great on any laptop. They know or have heard that "PCs and Macs are different."
When a reasonably prudent consumer hears "linux just works, well at least it works on my thinkpad" they might get the impression that the same can be said for any other "PC laptop." For the vast majority of the computer using population thinkpads and dell/acer/etc laptops are essentially interchangeable. Unless people know of the long and torrid romance between kernel developers and the thinkpad they will be oblivious to differences between thinkpads and every other major laptop brand.
I take it that you are not a linux+thinkpad user?
I'd rather just get back to hacking.