Blizzard Entertainment is one of the few other game developers alongside Valve who only release games once they're finished. It's called the "It's done when it's done" mantra and has led to Blizzard releasing numerous successful games that everybody loves. It seems they are ditching that philosophy for Diablo III.
Blizzard announced on the official Diablo III blog that the PvP arena section of the game was not going to be included at launch. The reason being that it didn't live up to their standards. Does that mean that PvP is out for good? No, it just means that they will be adding it in post-launch through an update.
Fret not though, as Blizzard says the lack of PvP at launch only means that they will be able to deliver the best single-player and co-op content on time. If they were to delay the game just for the PvP, they felt that it would be punishing to those players (like myself) who only care about the campaign and co-op content.
It does sound like they are being rather ambitious with the PvP, however, with the blog post detailing all the work that's going into it. Once it does launch, it will include "multiple arena maps with themed locations and layouts, PvP-centric achievements, and a matchmaking system that will help you and your team get into fairly matched games quickly and easily."
As for the campaign, they are putting the finishing touches on the game. The only thing they lack now is a solid release date. At an Activision conference call earlier this year, it was stated that Diablo III would launch sometime in the second quarter of 2012.
While some fans may not like this new Blizzard that cuts content to get a game out on time, I for one welcome this new Blizzard. While it's important that teams take their time on a game to make it the best it can be, it's equally unfair to delay a game for a feature that maybe only half of the player population would take advantage of. I didn't complain when Space Marine didn't launch with its arena co-op mode, but it was a delight to get it a month later when I had finished with the campaign. As long as the PvP arena stays free, Blizzard made the right move here.