Casey Spencer wrote a review of Mammut Smart Belay Device on October 31, 2011
I was a little apprehensive of buying the "Smart", as I know a lot of people who love the Gri Gri and similar devices. I thought you had to spend a lot of money to get an auto locking device, but I was wrong. This device works great, especially for the price. My wife, was very apprehensive of belaying me, used it and did a great job; she said it was very easy. The only issue I have ran into is the same as most of the other users, it is a little jerky when lowering a person and it is easy to short rope someone when they are leading a route. After a while you'll learn to find the sweet spot and get a good feel for it, just take some time to play with it on some warm up routes so you don't short rope your climber as their climbing a tough route.