This looks so much like our dry creek bed with our little apple tree in the middle. Maybe adding large rocks around the other side of the tree will make it feel more balanced. Also, I like the itty bitty rocks along the outside of the larger rocks.
Elite Cascading Falls: Large Kit - If strong water flow is the desired effect, then the Elite Large Cascading Falls Kit will give you a big enough liner for water storage (15'x15') and stream size (10'x20'). Pump flow: 6,500gph ideal for streams as wide as 5ft of water flow.