I didn't have a whole lot of expectations going into this one, despite having seen the trailer a few times, and overall, that may have been a positive thing.
Krampus does many things right - the atmosphere is appropriately bleak and frigid, with multiple well-done scenes depicting the cold Hell this extended family has found themselves in. Most of the comedic elements are decent, and I've no complaints about the acting of any of the characters, which is of course another plus. The flashback, as narrated by the grandmother, was done in a rather enjoyable animation, and thoroughly enjoyable to witness. The Krampus' design was pretty solid. Even most of the ending worked for me.
Of course, few movies are totally without flaws. At times, the amount of dangerous creatures got a bit much (a teddy bear, gingerbread cookies, an evil angel, a Jack-in-the-Box, and a toy robot, for instance), and while I've no complaint about most of these, I thought the gingerbread men were a bit ridiculous. Toward the end, when the pit to Hell (presumably) opened, I was finding it more difficult to care than I'd hope for (if only because I expected some twist to come up, rendering the whole thing moot).
And while the ending scene itself was actually pretty cool (the snow globe workshop was indeed fun), the last split second was a jump scare, with a bunch of evil toys coming at the screen. I abhor endings that try to scare the audience (not a character in the movie, but the audience) in the last split second. It's over-done, and ruins any chance that the movie could be spectacular. All-in-all, Krampus is a good slice of Christmas horror. Plenty of the actors and actresses stand out (notably Emjay Anthony, Adam Scott, Stefania LaVie Owen, and Conchata Ferrell), and while not the best Christmas comedy-horror film out there (Santa's Slay, anyone?), it was certainly worth a watch.