Update Dec. 28: The comet has reached magnitude 5.0! It's in Lepus, easily visible now from northern latitudes in late evening when Orion stands high. Tonight (Sunday) it passes by the globular cluster M79, which is smaller and much fainter at magnitude 8.4. From Sky & Telescope's hometown at latitude 42° north, the comet is a big puffball in 10×50 binoculars even through suburban light pollution. It appears moderately concentrated toward the center, with a hint of being asymmetric but no visible tail.
Below are some useful star charts should anyone want to step outside and take a peek.