Hi, I installed the AMD64 version of Ubuntu a couple of days ago now, and I'm mostly very impressed. However, I have had a few issues - the main one being a couple of system lockups.
The first time was when I inserted my usb memory stick, and the second time I was doing very little except playing an audio CD through xmms and browsing with Firefox. Both times I had to power off and start up again - ctrl-alt-del wouldn't do anything and worryingly my reset button didn't do much either.
It also fails to get the system time from hardware on startup, but that's no big problem right? After all, it syncs to an ntp server and shows the right time.
And finally I'm having problems with ripping CDs, although I haven't spent much time on fixing that one yet.