I wasn't actually able to use it because the servers were overloaded. What exactly impressed you (or more generally, what does it actually let you do at the moment?).
What you get is a 3D room based on the prompt/image. It rewrites your prompt to a specific format. Overall the rooms tend to be detailed and imaginative.
Then you can fly around the room like in Minecraft creative mode. Really looking forward to more editing features/infill to augment this.