Paranormal Activity 2 (PA2) is a tricky film to review accurately; it really blurs too many lines and it a lot of ideas will simply come down to a difference of opinion/preference between people. Much like its predecessor, PA2 will divide a lot of audiences between completely loving it and thinking it's ridiculously scary and intense, hating it and think it was stupid from the start, or just liking it in general without really leaning in a "it's stupid" or "it's genius" way.
This review may contain mild spoilers.
To start off, if you weren't Paranormal Activity 1's biggest fan, you probably won't be transforming your hatred into love any time soon. PA2 builds upon the original premise with, essentially, the exact same formula. Then again, I wouldn't completely advise haters of the original to steer away from the sequel, considering it at least attempts quite a few new ideas and techniques that weren't present in the original.
The biggest addition is the series of surveillance cameras set up around the rather large house instead of just the one handy-camera like the original; however, note that there is also handy-camera footage in this installment just like the last one in addition to the stationary cameras. This idea and these scenes are brilliant and definitely add a new level of depth to the regular sequence; not only are there more scenes to take in, but they're being shot 24/7 and are never tampered with. Therefore, the scenes that are a bit obscured from the handy-camera footage are in full view, sound and all, with the surveillance cameras. Unfortunately, they're not really used to their full capacity; there are scenes where, for some unknown reason, a handy-camera is used to capture footage that is already being recorded, much more reliably, by the surveillance footage. The surveillance cameras were installed after an assumed "burglary" in the home, and are used to review whenever strange events occur, but when said strange events do occur, it takes a bit of time for anyone to realize or be coerced enough to actually look at the footage. Logically, that might be the first place you look when someone gets locked out of a house or, I don't know, hears a thunderous bang or alarmed barking of a watchdog somewhere away from your immediate attention. Also, one of the cameras virtually has no purpose, considering nothing ever happens in its point of view.
The next big additions are the elements of an infant character and an animal. These characters could go so many different ways and add completely new dimensions to the 2-similar-character didactic. This is a full-fledged family: mom, dad, daughter, baby son and dog and even a maid! The baby, Hunter, and dog, Abby, are extremely similar in that they see and experience certain things that no one else does or can (like seeing something otherwise invisible). This seems to be where their roles stop, though. Their only real purpose is to give you the chills when they react to something you nor the other characters can't see. Hunter's role is vital due to his relevance within the film's mythology; that is, PA2 and PA1 are connected in sequence and play into each other's plots. The dog, although lovable, is almost completely useless if she didn't give an excuse for a pivotal plot point to take place later. Both characters could've been utilized to a much greater effect, but were not. Hunter's very existence is for the shock value of having a baby being the main character in a a potentially violent, scary film.
The environments are more varied this time around, with a swimming pool being the most radical change. Again, none of the scenes are used to full potential with what could have been done; this rings especially true for Hunter's nursery, where a giant in-your-face-mirror (which provides opportunities aplenty for a horror film) is hardly utilized other than reflecting some scenery that seems harder to see due to the surveillance camera's placement.
Another important fact to note is that many scenes from the trailer(s), and I do mean many, are not included in the final product, or at least in the final product I viewed. I'm not entirely sure if audiences around the world are seeing the same exact film, so my opinion of the film may be skewed a bit.
The script is weak. Weak weak weak. Far too many scenes exist where certain pieces feel forced and extremely scripted in a context that's meant to feel the exact opposite. Lines feel downright corny and some scenes play out in a generically cliche manner. It's tough to deduce whether the actors are the ones screwing up with, well, bad acting, or if the writing was just pedestrian. Luckily, most of the scenes are actually acted out pretty well; anyone who might think the acting was awful should realize that these actors are most likely using their own personalities as models for their characters. Everything is supposed to be "realistic," more or less, and it tends to feel that way. This is largely due to the "normal" look of the actors; you won't see any caked up models or chiseled chins around here. The characters seem like perfectly normal people that you could/would encounter in every day life, and they react to situations in the same way many of us would. Then again, a good chunk of their reactions are questionable and a bit unrealistic, but unless you have encountered a demon in your home, you can't really pinpoint exactly how you would handle things.
This all being said, the scares are what PA2 will most heavily be judged upon, and thankfully scares abound in this sequel. Although many of the scary moments are simply startles, with some dynamic event taking place on-screen accompanied by some boisterous thud, there exist a few golden moments of sheer suspense. I'm not saying it takes overwhelming amounts of talent to have almost no noise present and then just smack the nearest hard object, but it does take talent to do it repeatedly and keep you drawn in. This is where PA's hate-it-or-love-it formula kicks in: within every static shot of a scene, you're basically playing a miniature game of "Where's Waldo?" except, of course, you're playing "Where's the Creepy Slowly Moving Thing in this Shot?" This will either try your patience or excite you upon seeing the quintessential Day/Date caption on a scene; personally, I enjoyed it. To me, it gives the viewer a bit of interactivity by, in a way, "playing along" with the film's formula. In the original PA, the only place you could really look closely for activity was the doorway, otherwise the action you needed to see would be blatant. In PA2, there are at least a few different pieces of each set to pay attention to, like something swaying from the ceiling, a doorway exposing a shadow or a mysterious light or wind emanating from a window. There's also a ton of foreshadowing and allusion, which is fun to catch when you see certain things later on. One of the biggest gripes I had with the first PA was that, although I loved it, it wasn't a very re-watchable film. It's great once and it's great to watch with the uninitiated, but the scares become contrived and there's only so many times you'll jump at something. With PA2, this is practically the same idea, but at least there's a few things here and there to look out for. Another crucial element of the PA series is a somewhat ironic one in that waiting and closely listening are the most exciting parts of the film. Just because nothing is actually going on on-screen doesn't mean nothing is happening in your mind or within your attention span.
All in all, PA2 isn't any sort of triumphant victory as far as sequels or horror films go, but it's definitely a good sign for the series. It utilizes enough new material, albeit not to its full potential, to at least draw in audiences and get you talking. It's still just as suspenseful and the ending is just as, if not more brutal and poignant than PA's. In order to truly enjoy the film, it's necessary to put yourself in the film's atmosphere and not just anticipate the gimmicks. Believe that the film is recovered footage from a haunted house and believe these characters do exist and, most importantly, don't expect anything specific to happen once the nighttime scenes take place. You must also remember that part of the fear of anything paranormal-related is the whole mystery behind it. Forget how any events occur or even why the phantasm is performing them and be more concerned with the fact that anything "spooky" in the film is even happening at all. Follow all these steps, and you'll most certainly enjoy the film for what it is as it helps usher in a new brand of horror films.