Apple has released first time a beta version for public download which will help the company to understand the bug fixes and errors more deeply because more inputs shall be available from public users.
Jailbreak users must keep in mind that they will not be able to jailbreak iOS 8.3 and if they are willing to give a try to 8.3 beta they should use a spare device or compromise on their jailbreak.
The iOS 8.3 Beta includes improved performance, increased stability, bug fixes, and a redesigned Emoji keyboard. This release also supports additional language and country support for Siri: English (India, New Zealand), Danish (Denmark), Dutch (Netherlands), Portuguese (Brazil), Russian (Russia), Swedish (Sweden), Thai (Thailand), Turkish (turkey). This is beta software that is still in development, which means some applications and services may not work as expected. Follow the instructions below to enroll any iOS devices to receive beta updates.
After signing up for the developer program from below link you will be asked to download a profile to your iOS device. After which configuration profile will allow the iOS 8.3 update to appear in Software Update section.