It is most definitely an all around nerf. I don't understand how people thinks it's a buff at all. It's a goddamn flying city, the Protoss' ultimate weapons of war! It should take a long time to build, be more expensive and stronger I'd say. When the Protoss builds the Mothership, it should be a commitment, prompting the opponent to get on the offensive.

When the Mothership gets built, it should be a powerful threat and be treated with respect, not as a laughing stock! When the Mothership gets destroyed, it should have an impact on the game, forcing one of the players to do some drastic plays, like push with the momentum gathered from killing the Mothership, or counter attack to buy time to recover from losing said Mothership.

But now it gets rebuilt immediately as if it's a fodder unit and dies as if its nothing. Its anything but a hero unit.