I purchased it a while ago but I thought it may be helpful to write a review on it.
The Shedender comb works very well when it comes to taking out the loose and undercoat hairs but the comb is just so small that it makes it really hard to use. You have to go on one direction and the way the handle is, it makes it hard to switch sides like you have to do when brushing out your dog. I think I heard that that have made some improvements since, but it still looks like it could be a pain to use.
So overall, it works to an extent but the comb is too small for a large dog and it is a pain to use.