I will admit, when Sofi first saw it and tried it on, she HATED it! Today I finally convinced her that she had to at least let me take pictures of her in it, she changed her mind. When she saw how easy it was to use and still buckle herself (that independence is important!), she declared she LOVED it!
I don't think it'd be good for days where the child is running around and playing outside. But I do think it's great for running errands, or just a drive from point a to point b. It's also great for layering. Afraid your child's thin fleece carseat-safe coat isn't going to be warm enough for the cold winter? Add a poncho on top! Sofi could easily wear her thin fleece coat under the poncho, and if she gets too hot in the car, unzip it to cool off a bit.
Put the Poncho on the child when she's in the warm house. Have the child sit in her carseat and put the back part above her head, on the seat.
Unzip from the bottom to buckle child or have her buckle herself.
Make sure harness is properly buckled and tightened. (note, in this picture, the chest clip is still low and needs to be raised)
Zip the poncho back down to keep her warm.