As you can see, they aren't flat, they have shadows, uneven laid and, they aren't carbon copies of each other. In fact, I'd dare to say that this is the most realistic wall I've ever done that had 0 displacement applied to it. GOD really helped me big time on this one!

Now, it is fairly easy to make, because you will be using wood textures. Ironically, just giving you the node setup will mean nothing, because there are custom values for each distortion node and even the ColorRamps, but basically it works like this:
   When you add a wood texture, you get diagonal lines. These need to be rotated to go along the wall and sharpened to give us a black and white stripe appearance (very little fading). This forms a mask, so we can have interleaving bricks.
Now, using the same wood texture, with distort category nodes, add your vertical mortar lines. If you add them into a viewer node, you should see upright rectangular shapes running in a diagonal pattern. Using the original mask, you simply adjust and shift it, to form your horizontal mortar lines. If you followed the instructions and you know how to use the Color > Mix node, you should have a clean brick mask atm.

   To make the bricks a bit misshapen, you simply distort the mask we now have, with a cloud texture or whatever other texture you wish.

   And there you have it, a clean brick mask. Feel free to add more clouds and other things to make it more bump realistic and before carrying out, add a Value To Normal node from the Convertor category.
Here is the node system to mine, in case you wanted to follow along: