One of the problems with recommending Ubuntu to potential future users, especially those not particularly given to technical endeavours, is that there is a chance that upgrades will break their machine, and they'll have to pay or otherwise coerce some knowledgeable person into fixing them.
In my limited experience of running successive versions of Ubuntu since 8-something on a couple of different laptops, this chance is quite high. I'm not sure if I'm just unlucky with the hardware that I'm using, or if it's a result of the higher-than-average number of packages I have installed, or if upgrades are just typically problematic.
So I'd like to know the likelihood, for a casual user, of doing a release upgrade, for example from 10.04 to 10.10, without experiencing any regression bugs.
Obviously this is dependent on the hardware that people are running. Canonical seems to be making some efforts towards collecting data on this, for example with the "I am affected by this bug" checkbox on their issue tracker, and with the laptop compatibility reports, but I've not seen anything comprehensive.
I'm hoping for an objective reference here, for example a study carried out by relatively unbiased individuals. However, anecdotal evidence is probably useful too.