Sometimes a coffee table that isn’t the standard height or width is exactly what a room needs. In this instance a very low coffee table creates a crisp horizontal plane in the foreground, offsetting the long horizontal line of the credenza in the background. A higher table would have blocked the view of the credenza and competed with it; the varying heights add interest.
Coffee tables should be the same height as the surrounding seating, with 18 inches being a good average (although it will depend on your furniture). If you select a coffee table with a lip, make sure the lip isn’t higher than the adjacent seating, or you’ll end up hitting your drink against the lip when you try to set it down. The idea is to put your drink down, not up.