I had one on a recent trip - I didn't reserve it that way, but that was what they delivered. I tried it for a couple of days, but it was very cumbersome. It really did restrict my view, and made using the busses really tough. It was left at the hotel room after that!
I liked the idea of the shade, but Disney does a good job with ride lines being covered for the most part anyway. It really was onlly helpful getting between attractions - but the reduced visibility cancelled all that out. I am too afraid of running over someone who cuts in front of me anyway - the canopy worsened it.