When I test drove, the car they gave me had the armrest extension. Being 17 i suppose that my arms are not as long as some of you but when I would shift, my elbow would hit the corner of the extension. I'm sure that if i varied my driving position that i could remedy that problem but its just not worth it to me. Some people love it though, if you have long arms, by all means, get it. It gives you something for your arm to sit on
Also, i dont think it is easily removed, installation should be pretty simple though, don't quote me on that though.