Cool! Spacing between rocks and plants looks really good. Are you going to try some live plants?
Also, i would move the fake 'cabomba' plant over about an inch to hide the heater.
Did you silicone those rocks together, the one that looks like it's tetering a bit?
Nice tank. I would recommend putting the heater horizontally in the back of the tank about 2 inches or so from the substrate. It will be hidden and it can more efficiently heat the tank.