Ubuntu 14.04 is the next Long Term Support Ubuntu version which means Ubuntu 14.04 LTS will be supported for 5 years for Ubuntu desktop and server, Ubuntu core, Kubuntu, Edubuntu, and Ubuntu Kylin. All other flavors will be supported for a time span of 3 years.
Ubuntu 14.04 LTS codenamed Trusty Tahr, is releasing today on April 17, 2014. The Beta versions were available for download but the stable version is releasing today. You can wait to see it when the download link for Ubuntu 14.04 appears on the Ubuntu download page.
Upgrading from Ubuntu 13.10
Open Software Sources and press Alt + F2 to open the command box.
Type update-manager and open it. You will find the option New distribution release '14.04 LTS' is available.
Click upgrade and follow the steps to proceed.
What's new in Ubuntu 14.04 Trusty Tahr.
You can have a first look of Ubuntu 14.04 Trusty Tahr from PuppyLinuxWorld.
A comparison of Ubuntu 14.04 LTS to the last Long term support release 12.04.
You can read the press release Here.
You can try Ubuntu try Ubuntu without installing through booting from USB/DVD or you can install install linux ubuntu on oracle vm virtual box.