Doomsday Clock was reportedly going to signal the return of the JSA and the Legion of Super-Heroes. Both those teams returned elsewhere this month. That means the purpose of the series now remains to explain how the DC Universe was altered by Dr. Manhattan and essentially be a sequel for Watchmen.
I've been reading Doomsday Clock primarily because I feel like I have to, for this web site. With Before Watchmen, I felt like it was an unnecessary cash grab from DC Comics. There were some fine creators that tried to the best that they can with it. However, I'm unclear on the reasons for Doomsday Clock except to fix problems from DC's biggest marketing scheme of the past decade, the New 52. Watchmen is being rolled into it for some indiscernible reason.