LibreOffice is still not playing nicely with the Unity interface of Ubuntu. For a start, it does not support the global menu. You can enable this by installing the lo-menu package (available in Ubuntu software centre). This doesn’t work for me though; after installing the Window menu disappears. This means loosing access to the split and freeze functions in Calc.
Edit: The solution mentioned below does not work in Ubuntu 12.10. See here for more information
I can easily live with a lack of the Global menu. More problematic is that the LibreOffice icons on the Unity launcher tend to become unresponsive. At the same time, the open LibreOffice documents do not always show up when using Alt+Tab to rotate through open documents. If this happens, the only way to access your open LibreOffice documents is using the Superkey + w key combination, which is a far from perfect solution.
There is a temporary solution to the problem of freezing icons on your Unity launcher. You can run the unity –replace command, which will restart Unity. Don’t run the command in a terminal, you’ll have to keep that terminal open the whole time. Use the Alt+F2 instead to open the ‘run application’ Dash* and type in the command.
Unfortunately, this is a temporary solution, the problems will reappear at some point in time, after you’ll have to run the command again.
* On most Linux distributions Ctrl+F2 will open the ‘run application’ window. The ‘run command’ dash on Ubuntu is essentially the same, just a different interface.