Not useful at all.

I bought this from Amazon hoping that I won't need to carry a blanket when I take the baby for a ride in the car or the stroller. However, it turns out that a blanket is much easier to work with than this. The two sides of this bunting bag are made of two different fabrics, the exterior is smooth while the interior is less so. After laying the bag in the car seat or stroller, it tends to move away from where I want it to be, even thought there is an elastic strap that was supposed to secure it to the seat. Then once I put the baby on top of it, it is hard to adjust the baby's position because the fabric tends to stick to the baby's clothes. It is tough enough to handle a wigging baby, and this bunting bag makes it even more difficult to adjust the baby's position. The bag looks nice and neat in the pictures online, but for all useful purposes, it's not much different than a piece of towel.

I ended up using an Old Navy fleece pullover ($10) that I no longer wear as a blanket for the baby. When it's windy or cold, I cover the baby with the fleece pullover, pull the sleeves to the back of the car seat or stroller seat, and tie a knot there so it stays where it should be. It is light enough to tuck in the stroller basket, easy enough to drape over the car seat canopy, and convenient enough to tie to the diaper bag that I carry.

This product is the only baby product that I find completely useless.