We acquired a booster like this from a friend. It is lightweight, durable, and SO EASY to get in and out of car or to get a child into it. We thought about getting a replacement cover for the one we have, but found THE PRICE TO BE SO GREAT that we just decided to replace the entire unit. In fact, we got TWO more - so grandpa and grandma could have one each too! I like the simple color scheme - especially for my dad's car. ;) The arm rests serve to provide COMFORT for little tired arms (However, they need to be able to rise a little higher or be removable for taller or larger children.). Additionally, the armrests create greater stabilization (i.e., ADDED SAFETY!) for the rider. I am so glad they are there! And, the cup holders...I wouldn't want to live without them!!! They are great for drinks, snacks, and even as a compartment for little toys, crayons, or stuffed animals! Thanks for including two in your design! Overall, I am very pleased!