The personalization items are free, too
Nuketown (you can't make me swap out that "e" for a "3") was available as a pre-order / early-run bonus map in Call of Duty: Black Ops III, but as of today, latecomers can also play on it. For free. If they'd like. It joins the main map rotation in "a variety of multiplayer playlists," and Treyarch is also enabling a nothing-but-Nuketown playlist until Monday, March 28 at 10:00am Pacific.
Elsewhere in today's update, Black Ops III players are getting a Nuketown-themed weapon camo, three weapon reticles, and a calling card. More than messing with any of that, just be sure to activate the map's unsettling robot people (and then wish you hadn't while hiding under the covers).