I never saw Paranormal Activity, but I'll see the sequel some time this week. If you can make an opening and closing door genuinely scary then that is, in my opinion, a considerably more admirable feat than having someone saw off a backpacker's head.
I know a guy who makes that kind of suggestive horror. Speaking of DOORS....
http://vimeo.com/2794940
Just so you know, PARANORMAL ACTIVITY 2 explains what happens before and after PARANORMAL 1. Katie and Micah are in both. I would suggest seeing the first one, otherwise, you might be confused near the end. Or, watch the end of the first one on youtube, then watch the second movie:
PA ending
Part 2 is has the same style and is better acted, I think. It might be a good choice to watch first, if you understand what happened in the original. Whichever one you see first, is the one that should get you.
As far as gore, I think there is a difference between a really effective makeup gag and gore for gore's sake. Also, I don't want to see innocent people get tortured, but I do like seeing a bad guy getting his just desserts.
I've followed artists like Tom Savini, Rob Bottin and Rick Baker, so I have a keen interest in seeing cool makeup. That is as much of an art to me as any other filmmaking element. That doesn't mean I want to see "torture porn," but I love all the original gags in movies like DAWN OF THE DEAD, specifically the effect where a zombie stands up into the rotating blades of a helicopter! To do that, the blades were animated and the zombie actor was given a high forehead that could be pulled off with fishing line. Very clever!
https://www.youtube.com/watch?v=55fMHSA-16c
Movies like Peter Jackson's DEAD ALIVE have so many funny gore gags that it is amazing to watch a zombie's intestines chase after the protagonist throughout a few scenes!
Of course, the Kung Fu priest is awesome:
https://www.youtube.com/watch?v=Zvt1ZM1_5Ao
Credit John Carpenter's THE THING for some of the best makeup fx gags ever. The head that sprouts spider legs and walks off, is classic!
https://www.youtube.com/watch?v=TevQS4qgE_Q
I also like anything transformational like werewolves in THE HOWLING or James Woods sticking a pistol into his stomach, in VIDEODROME.
https://www.youtube.com/watch?v=a3RuGJCMVAQ