To be specific: Spiderwick is a movie that runs along the same theme of child fantasy as a number of other recently released movies (Chronicles of Narnia, Golden Compass, Enchanted, etc). It seems to me producers saw the amount of money made on Narnia and thought to themselves 'hmm, kids like fantasy movies now, ok we'll give 'em fantasy then!' Despite the lack of genre originality, the story was alright. Basically this kid finds a book with a warning note attached to it instructing that it not be opened. The kid (of course) opens it anyway and all nil breaks loose. So then he and his siblings go on a long quest to fix the problem and end up fixing it permanently rather than halfway (like it had been fixed before). The plot wasn't 100% original and seemed to be a (slightly messy) mix of ideas inspired from other stories. I don't know how well the movie followed the book, as I never read the book (or series or whatever it is). Sorry! The special effects were pretty good, and I liked how they kept the big goblin hidden from view for a little bit. It increased the sinister mystery of the bad guy (I always like that bad guy effect).
All in all, this movie was made for kids with less-than-critical points of view just looking for a cool movie to watch on a Saturday night with some friends or their parents. As for everyone else, it would be slightly more interesting if one or two people got mauled and maybe if the griffin flight was a bit more extreme.
To be specific: I can't believe so many people are giving this movie thumbs down simply because of the filming style. So what if it gave you a little motion sickness? Get over it. The filming style was the BEST part - Blair Witch style (if you really need comparison) but much much bigger and better. The special effects and acting were so remarkable, the movie pulls you from your seat and makes you feel as if you're actually there witnessing the whole event. Lots of chaotic dying maintains the morbid atmosphere, though most of it isn't gruesomely gory unless you have a particularly weak stomach. There is next to no music (it's a 'live action amateur' movie) which is for the best to get the 'actually there' effect. The movie opens as if it's a video found by the US government and is basically a piece of top secret evidence to be viewed and studied. The ending breaks off into a cliffhanger, and doesn't add too much in favor of the opening or provide anything in terms of an explanation, leaving viewers mystified and confused and making an excellent conversation/debate topic (again, much like Blair Witch) or leaving viewers unsatisfied and agitated (who are probably just lazy, lack attention spans, and/or feel uncomfortable with breaks from the generic, like previously mentioned). The beginning, being a (yes, somewhat long) sequence of a going-away party for one friend, is perfect for developing the main characters and creating an overall feeling of familiarity and empathy for them. The rest (majority) of the movie portrays the group of friends traversing the ruined city on a mutual quest trying to avoid the main monster, as well as other obstacles, the group getting smaller as they go along. Many of the scenes (and ideas) are unique and inspired, giving a fresh feel to the suspense/horror genre in a glamorous light.
My only complaint about this movie would be *SPOILER* the lack of gore when the main filmer is killed by the monster. He is standing under it frozen in terror, filming it up close and personal. The next thing you know, the camera is rolling and going crazy. As suddenly as the attack happens, the camera is on the ground, showing the filmer lying next to it. Unfortunately, the camera only picks up his head and part of his chest, so you can't tell what happened to him - whether he just got battered or if he's missing the lower half of his body or what. Judging by the two friends' reactions, one would assume he's not in terrible shape, so it was rather disappointing to watch as one would automatically assume he's being eaten or something similar as the camera begins wildly waving about. Out of the entire movie, that was the most (and possibly only) regrettable portion to watch.
All in all, I would most definitely recommend this movie to friends (that aren't prone to motion sickness). Even if someone ends up not liking it, this movie is a new enough style that at least they'll find out for sure whether they really like it or not. I literally walked out of the theater trembling after I watched it. For those of you constantly comparing this movie to Blair Witch, I implore you to not refuse to watch it simply because you didn't like Blair Witch. Cloverfield may be similar in filming style, and may be in the same genre, but the storylines are not the same in any sense whatsoever. Just because you didn't enjoy Blair Witch doesn't necessarily mean you won't enjoy Cloverfield.
Extra message: If you're lucky enough to still have this playing in your local theater, GO WATCH IT ASAP!! This movie is a theater movie, so unless you have an enormous home entertainment system with surround sound and a huge screen with great picture in a room you can easily darken, you absolutely must watch it in theater. It's a must-own movie, but the effect is a thousand times better appreciated on the big screen.