It's like a Big Bertha and a Mortar fused - the Small Bertha is the size of a mortar, but it has higher range. You can choose where it will fire, but in limited range and smaller damage than the Big Bertha's one. A shoot will cost like 50 energy. It will be like 2x stronger than the Mortar. Basically a cheaper version of the Big Bertha.
Sounds more like a buffed mortar with a side of micro management :D