I live in New York and primarily ice climb in the Catskills, Adirondacks and Ouray, Colorado, which all witness drastic temperature changes from -5 to 45F in winter. This jacket accomplishes exactly what it was designed for: keeping you warm while belaying in wet conditions. Down belay jackets, such as the Arc'teryx Ceres, which I also own, are warmer if dry. However, if you become wet from melting ice/snow and need to pull a puffy warm layer over your shell between climbs, the down jacket options will fail when wet. The Dually Belay jacket uses a synthetic material that keeps you dry even when wet. It also does an excellent job of blocking wind and shedding light moisture (I haven't tested in rain yet, only under dripping frozen waterfalls). I usually wear a medium in Arc'teryx jackets and the medium Dually Belay fits perfectly. Please note that it is supposed to have a looser fit though in order to fit over multiple layers. It fits snugly in the bag attached in its pocket and can be easily clipped to the back of your harness for multi-pitch climbs.
This review was written in the old system and had content requirements that are different than reviews written today.