(Prepare for an essay)
First of all, I thought the drone paths weren't bad. They made the level fun and challenging. I wasn't much of a fan of the chaingun though. It tended to get stuck in small passages, which you would then have to wait for until it made its way slowy out. So I think you coud take that out, or change its path.
The room with the gold was particularly fun, but no one likes it when enemies are stacked, so stick to one, preferably the rocket. Finally, I think your tileset was good and worked well to contribute to fun gameplay. I think you could have made it a little more attractive though.