After playing a bunch of it, I just don't see what gametypes Wreckage was designed for. The asymmetry and Halo 4's atrocious spawn system ruin CTF on it, Ball consists of camping either on the hill or in the red base ramp corner, King has insane framerate issues (but is otherwise acceptable).Shatter is hardly the worst map. Shatter is good, Harvest is just as nice (simple layouts are always appealing), Wreckage is absolute hot, smelly, 2am Taco Bell diarrhea. The map screams camo, PV, and Boltshot abuse (the damage range on that thing is absurd), close quarters with ridiculous amount of hiding spots, and one side of the map is blinding when you look in that direction (which you have to on a regular basis. I'm sure there's more, but I've been quitting out whenever that map is chosen by the unwashed majority. Wreckage is right up there with The Cage as one of the worst maps to ever disgrace the Halo franchise.
Harvest is pretty obviously a CTF map and is okay, though again, the spawn system has ruined several games of it for me. It manages to have some interesting routes but I definitely see top glass camping being a problem in the future. Then again, the issues I've run into with that almost entirely stem from the CTF changes, which I think are a net negative in the first place.
Shatter is an interesting one. It has so much potential with the right gametypes. The few games of CTF Shatter I've managed to play have been some of the most fun I've had with the entire game. It has flag routes that are more than "Do I go into this hallway or the other hallway?" with the ramp/tunnel to mid or the teleporter to the seconary base. But it almost never shows up, leaving King of the Hill and Extraction as the predominant gametypes on it, neither of which I think work well on it. It could use a Warthog or two, as well.