This is probably a good general overview, especially seems as how the AF likes to claim it could replace the Navy every now and then.
PGMs and
DPICMs munitions in particular allow a lot of tailoring to target and tend to be more effective then raw HE due to the spherical volume raising energy requirements by the cube effect. The Zumwalt's guns are meant to be analogous to 155mm batteries as per USMC specifications for what they want from NGFS assets. Larger caliber especially if more inaccurate guns tend to be less useful due to friendly fire considerations and otherwise.