Despite temporarily disabling certain features on PSN, it seems as though the online service is struggling under the stress of gamers pouring onto the PlayStation 4's servers.
Earlier today it was confirmed that the What's New and Content Information Screen would be disabled, to ensure a positive online experience. All other features, including Trophies and livestreaming, were to remain online.
Sadly, it seems as though these measures weren't sufficient, as many gamers have reported issues logging onto to PSN and accessing online content. The issues were acknowledged on Twitter, and an investigation is ongoing: "We are aware some users are experiencing issues logging into PSN on PS4 due to the heavy traffic we are receiving, we're investigating... Thanks for your patience."