Good movie until an hour in... *spoilers* (sort of)

I was so happy to see a horror movie from my home country, cause the german film industry usually consists of comedy or drama. The few action and wannabe-horror movies are not worth mentioning. When I stumbled upon this little flick I was so exited...it had everything a "good" horror movie needs: a dark place, a sinister backstory of said place, annoying kids and a creepy killer - I mean, what more could you want?!?
And then it happened. At the 1h mark...

I give the movie credit for not letting the "hero" burst into the room and whack away at the maniac, even when his girlfriend was being tortured. Made it somehow more real. Afraid, waiting for the right moment, whatever. And when the creep is finally down...flashback to "Wolf Creek". (don't get me wrong, I like WC a lot!)

He could've split his head with the iron bar. He could've broke his neck. He could've done anything, for *beep* sake. Just make sure the guy doesn't stand up and stab you in the back when you're on the run. Take him out, eliminate the threat!

Okay, I hear all the horror buffs out there: But that goes against all rules in the horror movie rule book! So, what? There could've been more than one killer, right!? What about the rest of his east german "secret unit"??

Ruined the movie for me. DAMN!!! Still, the first hour is very well done and has a lot of atmosphere.