Well, of the three machines upgraded to Ubuntu 8.10 that I blogged about the other week, I've been mostly using the Sony Vaio notebook. Some issues have come to light (some good, some bad):
The new Network Manager (see the previous post for getting it to work) is brilliant, it's so easy to switch between wireless networks, and between wired, wireless and 3G networking. It's a joy after previous versions. So, definitely a huge improvement over 8.04.