Don't listen to Mizu, that was a short-sighted answer. You will be able to play on nexus servers in a similar isolated fashion as you can with BC2, we have been hard at work implementing mod support and getting overall product quality up. The "No" from Mizu was referring that we are currently in Closed Beta stages, which means if you do not have a VU key tied to your account, you will not be able to join any servers at this moment. All of this has been explained in the FAQ which is located here
kiwidog > NoFaTe.