These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
The wolf calls in general but especially the Alpha's.
Holy Shit Quotient: Just how much worse will things get for Ottway and his companions? The ante gets upped every. Single. Time.
Visual Effects of Awesome / Scenery Porn: They filmed in a real wilderness in Canada and it looks beautiful. The wolves are also not CGI, but (mostlynote they were digitally enhanced in many shots) animatronics and puppetry, and they still look really good...and TERRIFYING.
Hell, the film features Sound Effects Of Awesome as well. In the theaters you will feel the power and intensity of the plane crash and your bodies will quake from the sounds of the wolves. . .