Awful gun in PvP and PvE. You wonder if they even playtested it. It excels at no particular niche. Beyond worthless as it actually causes harm by taking your exotic slot.

Something very simple could make it go a long way to being better: melee kills should ALWAYS refill the mag. Right now it is a chance, and not particularly high. This alone would help the weapon so much without necessarily making it overpowered.

I think in general sidearms are in a poor place, since as a class they are kind of ill thought out.