I agree with jordy, the protein is denatured and so it is not healthy.
The reason it has been considered a "healthy" food is because of the low-fat craze. Rice cakes are fat free and very low calorie, so people thought of them as a healthy snack. The WAPF shows us that this low-fat craze was a fallacy. I would still say they are better than white flour crackers with hydrogenated oils, in a relative sense.
Of course the plain ones taste like styrofoam, and the flavored ones have other unhealthy additives such as sugar, corn syrup, artificial flavors, food coloring , etc.