The advantage of the APKWS system is two-fold: it does much less damage than a standard 500lbs or even “smaller” 250lbs smart bombs, which is great to avoid collateral damages. Also, the platform (plane, chopper…) carrying the APKWS may be able to carry more rockets (than bombs), which means that it could handle more target within a single mission. That said, a single APKWS remains extremely destructive, but less so than other laser-guided smart munitions.
As for the precision, the US Marines have reported that during tests on both static and moving targets, the APKWS has been able to hit with a 17″ precision from where the laser designator was aiming at. Needless to say that this is very accurate.