You can restore much of the look & feel of the previous version with these shortcuts:
- Ctrl-B to turn on the menu bar.
- Ctrl-S to turn on the sidebar.
- Ctrl-/ to turn on the status bar.
- Click the magnifying glass top right and untick Search Entire Library to restore the previous search behaviour.
If you really want you can roll back to iTunes 10.7. First download a copy of the 32 bit installer or 64 bit installer as appropriate, uninstall iTunes and suppporting software, i.e. Apple Application Support & Apple Mobile Device Support. Reboot. Restore the pre-upgrade version of your library database as per the diagram below, then install iTunes 10.7.
See iTunes Folder Watch for a tool to scan the media folder and catch up with any changes made since the backup file was created.