The Developer's Preview of WP 8.1 was delivered on April 14, but the official version won't be distributed to carriers until late May/early June. And even then, it will take some time for the carriers to distribute it...so expect until the end of the summer for the official WP 8.1.
It's your choice on whether you want to go this route, but I personally have had any problems with the WP 8.1 other than a slight increase in battery drain on my L920. If you do decide to take this route, and you don't like it, you can revert back to 8.0 following this thread:
After reading a bit about developers version i got confused , one of the posts was once you get it you can't update to official not sure what does that even means , also some have been complaining about some issues , like heat and battery life , so i was just trying to avoid such this that may annoy me .
Completely understand. You can update to the official update from the DP, make no mistake about it. As for the battery life, I can say the battery life does decrease, as I believe that having Cortana always on in the background is my culprit. I'll gladly take that slight battery drain to have it. My phone still lasts all day though, which is quite alright with me. I haven't had any heat issues with my L920 either.