My upgrade was from Ubuntu 8.10 to 9.10. It was done through the systems administration/ update app. It took a couple hours to go through all the process, but it kept all the previous configurations that I had done. That saved alot of time and effort. I would only recommend it to those with a fast broadband connection and bandwidth. Otherwise, it would take forever and cost more, if you only have PSTN. I chose to do this at an off time, late in the evening... when I didn't need the computer. I set it to update and by the time I went to sleep, it was done.
Youtube works fine, as well as Skype. Though the sound is scratchy... will have to tweek that. I was afraid that it would be worse after reading about bugs in forums, but there are no other problems. Even my bookmarks were saved. Recommend for those who don't want to have the hassle of starting from scratch, which would be true for a live CD. Otherwise.... best to make a backup copy of files,etc. and install with live CD, or burned copy downloaded from website. It is much faster.. only about 3o min.