I've been running Oneiric Alpha on a laptop, since the ati drivers in natty aren't new enough for the hardware. In general it's worked well; naturally there are the occasional crashes and bug reports. The strange thing is that--on occation--packages will uninstall themselves when I do an update. T
he first major one was unity. LightDM didn't have anything in the sessions menu, so I couldn't log in. I looked at .xinit files, searched all over, and finally figured out that unity had completely removed itself, even though it was the primary session type.
On another occasion, lightdm-greeter-gtk removed itself. Again, I had to hunt around in the logs to find that there was suddenly no greeter, although it had been working flawlessly for weeks before the update.
I'm not asking for stability--I know it's an Alpha. I'm just curious as to why packages decide to leave.