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.
Cliché Storm: The movie plays like your typical horror-themed arcade game. Two players with loads of guns and ammo, blasting monsters (witches) into ludicrous gibs, saving the hostage villagers (children), along with a Big Bad final boss. And the adventure continues. It also helps that the heroes struggle against powerful witches, much like how a stage boss takes a lot of punishment before getting destroyed.
Complete Monster: Muriel the Grand Black Witch is the leader of the Black Witches and the vilest one in existence. She tries to kill the Grand White Witch (Hansel and Gretel's mother) by using her heart in a ritual sacrifice to make evil witches impervious to sunlight, only to find that she was already burned at the stake by a human mob. Years later she and her two Co-Dragons kidnap twelve children to use them in a Human Sacrifice, after already boiling one down for a magic brew. She kills four trackers who were hired to rescue the children by letting their dogs maul most of them to death, and one by putting a curse on him that forces the man to eat maggots before exploding when he returns to Augsburg. She sets parts of the town on fire to kill the townsfolk as a distraction, and forces a guard to shoot himself with his own gun. She later kidnaps Gretel to cut out her heart as part of the new sacrifice. When this fails, she takes Hansel and Gretel back to the Gingerbread House where they killed their first witch before she murders the good witch Mina, whom Hansel fell in love with.
Draco in Leather Pants: The witches, particularly Muriel and her two crones (Horned Witch and Red-Haired Witch).
Evil Is Sexy: Muriel, when not in her witch face at least. Given that she's played by Famke Janssen this shouldn't be surprising.
Incest Yay Shipping: Most fans of Tumblr and Deviant Art have paired Hansel and Gretel together. The short-"haired" witch the siblings capture briefly taunts them with saying they should do this. Neither of them is pleased.
Muriel setting Hansel and Gretel's mother and father to be burnt at the stake and be hanged respectively, despite being completely innocent, especially since the former is a white, and therefore benign witch; in order to separate Gretel from them in order to get her heart.
Berringer crosses it when he murders the mayor in front of the townspeople.
Narm: The giggling, grunting, and rasping from the Horned Witch.
Ugly Cute: Edward the troll. He might look threatening, but his puppy-dog eyes are adorable.
Visual Effects of Awesome: The film employs a combination of digital and makeup effects to bring the witches to life. Edward is a completely practical creation.
What The Hell Casting Agency: Hansel and Gretel look to have only a couple of years' difference between them as children. Flashforward and... well, Jeremy Renner is 15 years older than Gemma Arterton and looks it.
More importantly, this is a completely non-serious movie with shotguns, hideous witches, and ridiculous amounts of blood and gibs. Why didn't anyone get Bruce Campbell for this film?
They missed an opportunity to show Sheriff Berringer being present at the burning of Adrianna.
And Then What?: The witches plan, to become immune to fire would not make them invincible, just remove a quite frankly rarely used way to kill themseeing as throughout the movie only two witches we see are actually killed by fire (one is the siblings mother, who did so willingly). We are given no real reason why taking away this one thing would help.