Ubuntu 13.04 (Raring Ringtail) is released and the Ubuntu website flaunts it now! Grab your copy from the usual Ubuntu download page or check the list of mirrors for a mirror near or in your country. If can also upgrade from older versions.
In my experience as a beta-tester for Raring this has been the smoothest Ubuntu release through daily dev and beta versions. It was only once that I got a kernel crash in the last few months though I used it as a power user tweaking things and experimenting all the time! It never felt like a beta other than minor glitches in userland applications time and again. Unity is much more polished and offers a seamless experience. The desktop is damn fast. Of course there would be criticisms but which newly released OS isn’t criticized? The point of Ubuntu/Linux is that they are so customizable that you can actually handpick features and mould the things you want and as you like.