Overwatch's open beta is now live, so let this put an end to the raging over invites and the suspiciously large number of streamers in the closed beta. Every map, every hero, every launch-day feature is available to try. Note that 'launch-day features' does not include competitive play, which has been pulled until some time after release for a redesign.
Overall, it's much closer to a demo than a beta (although not close enough that your progress will carry over to live). Blizzard must be confident it'll shine.
The floodgates are open until 10am PT (6pm BST) May 9. You don't need anything other than a Battle.net account and an internet connection to take part.
Overwatch is out May 24.