The low weight is good for long approaches, and small racking size gives you less clutter on your harness (triple them up to make alpine draws).There is a longer "cordalette" version of this that I'm not sold on yet. In case of a factor-two fall on the belay, the super static properties of the dyneema will increase the forces on your placements. For single and double slings though, this is not a problem because there should be plenty of dynamic rope out.Also, these don't last as long as nylon slings. Mammut says they are designed for alpine use and that you should retire them after only a few years of moderate to heavy use. But for the alpine they are hard to beat.
In case you live in a cave, dyneema slings are about the best thing going for alpine runners. Incredibly light, very small racking, and they dont soak up water like nylon. These wont be a durable for cragging use, but they cant be beat in the mountains. We use these skinny slings for all shoulder length (60cm) runners and then a handful of good ol' nylon slings for 48" runners if needed.The racking size alone is worth every penny.