I bought one and like it. The DVD is not great that is true. I use mine on both wrists but primarily on the right. I initially kept it on my left but found after about a week of chipping and pitching that the left was fine, now on to the right. On the full swing for me, it clicks going back from a centered club position and then clicks late during follow through (sometimes).
It is kind of pricely but I like mine and recommend it. I have heard others say use a ruler and two rubber bands to keep your left flat. I don't agree, it is worth it for me to kind of set it and listen for the click. Plus, it is not too bad to wear at the range. I mean come on, I have seen guys with swingjackets on at my range and the folks staring at them is amazing. I am almost sure a ruler rubberbanded to your arm would make folks look.
My two cents.