I experiment with it often in my stories, usually when referring to demon/non-human beings. Some will share the same speech type, some will have their own, and some can change in between them.
I definitely think they have their place, especially when you want to get creative and express tone shifts in different ways.
Though, it can becoming distracting if you don't always know how to use them. For instance, when I first started using them, I was really experimenting and changing up fonts and speech bubbles. At times, it got muddled, especially if the panels were already vivid. And sometimes, it was just too hard to read. But once I figured out a rhythm, it becomes more clearer.
These days, for demons, I use black bubble on white text. For more celestial beings, it's blue text on bubble or their own personal touch.