Ubuntu's automatic updates are regular and consistent, plugging security risks and updating drivers easily. However, you don't always get the latest bleeding edge updates. I've blogged about the getdeb and appnr sites, where you can download and install the latest packages without going through the official Ubuntu software channels.
There are caveats, of course; there may be trouble ahead. But while there's music and moonlight, it's often worth installing the latest Geany text editor goodness for example, and after all, what's the worst that could happen?
The Firefox web browser on the other hand is a different matter all together. So for you Ubuntu Hedz, you're best off using Ubuntuzilla, a python script that gets around incompatibility issues. On my personal machine, I haven't actually upgraded to 3.5 yet, mostly because I haven't noticed the lack of improvements. I think it will only be when my Firefox add-ons start breaking that I'll bother moving on up...