I decided to change the whole lancaster computers site and changed over from joomla 1.0 to the joomla 1.5 version. No there is a big difference between the two and certain plugins wont work as they are not available for the 1.5 version so you basically can plug the old modules etc into the 1.5 but you have to run it in legacy mode then. I used to use joomla stats and thought its pointless running in legacy mode and run te risk of security breaches so i added the google analytics for my web site stats which is probably better than joomla stats anyway! Well the main difference i do see is the optimisation options which are much better, the interface itself id say is harder to use but thats because im used to the joomla 1.0 version i suppose and will get used to the joomla 1.5 version. The module and com installer is different as you just have one installer now which can install from a local package on the machine or from a url which is handy, were we used to have three installers for modules etc which was a bit messy. Id say its a move for the best give it a shot take a look at http://www.joomla.org
Take a look at the lancaster computers site we offer a wide range of services. http://www.lancastercomputers.co.uk