Ubuntu 9.10 is available in the official Ubuntu website now.
1. Upgrade is recommended.
As per the Ubuntu community up-gradation is advisable. Refer it up for up-gradation: http://www.ubuntu.com/getubuntu/upgrading
2. New features
Refer http://www.ubuntu.com/products/whatisubuntu/910features for getting new features of the latest Ubuntu.
3. Download link: http://www.ubuntu.com/getubuntu