Good is somewhat subjective, when you're building a deep neural network to create images. Let's take a look at a few examples of the training process, so you can see for yourself how the GAN begins to learn to generate MNIST.
Here's the network at the very first batch of the very first epoch. Clearly, the generator doesn't really know anything about generating MNIST at this point; it's just noise, as shown in the following image:
But just 50 batches in, something is happening, as you can see from the following image:
And ...
