The major problem with this item is that it does not protect the straps from rain. So the straps over your shoulders and around your back will get soaking wet, and this will run through to your baby eventually. You could fix this by wearing the wrap under your coat, but then your coat is left open, and so you will get wet and cold.
This "weather protection" is only really any good as perhaps just a wind protection rather then rain. But to be honest for this price you may as well just buy your baby a pram suit and then pop them in the sling, which would be even more effective at keeping your baby warm, and just as ineffective at keeping your baby and sling dry.