I like this device very much
Upgrading to the ATC guide is far more convenient than my previous method of redirecting a hip belay on a standard ATC through the anchor master-point while girth hitched to a double-length sling clipped to the top shelf. The only drawback to belaying directly off of the anchor is the loss of a dynamic belay afforded by the other method, but I still think that overall it is far safer, especially because of the autolock (my second is still safe if the party above me kicks off a loose rock and takes me out of commission while I'm belaying her.) Lowering is a bit jerky, especially when you first start. Make sure to keep your hand on the brake strand when lowering to maintain control of the speed. For even better control you have to rig up a tricky little redirect which attaches the lowering hole to your harness, allowing you to control it with your body weight (be sure to add a prussic backup if using this method). Doing so isn't usually necessary in normal climbing; I would only rig such a system in a rescue scenario. The ATC Guide also allows you to safely belay two seconds at the same time, so that a party of three can climb as fast as a party of two (or a party of four as well; leader ascends, belays two seconding climbers, than begins to lead the next pitch as one second belays him from below and the other belays the fourth climber from above). I have no betta as to how this device compares with competitors such as the Petzl Reverso 3. I've heard that this works better with beefier cords and the Petzl works better with thin ones, but I have no personal experience to back that up. My main reason for buying the BD instead of the Petzl was that, with the addition of the grippy teeth (which I almost never use for standard belaying and repelling on my 10.3 rope) and the guide functions, this device looks and handles exactly the same as my trusty old ATC, giving it a nice feeling of familiarity.