Even though the delay was announced on launch its still strange that so long after release the PC is only now getting a beta for Metal Gear Online whereas the consoles had it for ages. The reason given for the delay is that Konami is still looking for an effective anti-cheat method and are currently strongly considering VAC.

As for the PC beta, during a short livestream the MGO team announced that Metal Gear Online will enter open beta starting at 10pm PST January 12 / 6am UTC January 13. 

In order to participate in the beta you will need to opt in to it through the Steam client by right clicking MGSV, going to properties and then the beta tab.

Metal Gear Online had a rough start, to say the least, when it first launched on consoles but after a whole lot of patches and balancing it seems that the public sentiment has changed and its now regarded as fun online mode which is great news for us on the PC given that we get to skip through the launch issues.

Though we might have launch issues of our own. As of right now its unsure whether any security system will be present in the beta and if there isn't I'm afraid you'll be forced to play the fun game of "dodge the hacker". Whichever the case hopefully the security system comes in as soon as possible and ends up being effective because otherwise no one will get to have fun.

Once the beta launches I'll give you an update on its state and whether its worth to get invested with it right now.