1- It doesn't allow autoconnect on start of application. Each time, you need to disable and enable your account to be able to connect to the chat server. By using the following technique, you can resolve this issue:
Open gconf-editior. In apps/empathy, untick 'use_conn'. That's it!
2- It doesn't support several chat protocols by default. To add more, just install telepathy-butterfly and telepathy-haze using the following command:
sudo aptitude install telepathy-butterfly telepathy-haze