Outfitters typically provide full mechanical support-spare tires, parts, and such. The weather is highly changeable, especially in the fall. Temperatures can range from blistering to bone-chilling. Rain and high winds are possible. A serious mishap would require a long, slow, bouncy evacuation.
Saddle sores are a common malady of the unprepared.
The Maze route is a more technically challenging trip than, say, the popular White Rim Trail in the nearby Island in the Sky district. Although much of the route follows smooth dirt roads, parts are quite technical. You should be adept at rapid shifting, picking a line, weight transfer, and lifting the front wheel Over small obstacles. Raw mountain-bike beginners probably shouldn't take this. Riders with intermediate technical skills will find this trip a bracing challenge and skill-builder.