I, personally, am a fan of the series, and I, after seeing all of them, know that these are definitely not for the faint of heart. Kids should not see this; the violence will most likely will be too much for them too handle.
Now I would like to make several points about this film. First off, this probably the best entry in the series, and if they end it now, they would be ending in a much higher note than the last one did. Secondly, I like the fact that they did not have any sex scenes (which the last one had). Also, although gory, this isn't the goriest in the series. More blood is shown here than actual insides of people (which the last one showed alot of). Another thing is, swearing isn't much of an issue here. The f-word is only used about 4 or 5 times, and not in sexual meaning. And the last and most important point is that this movie puts a several surprise twists. One thing I also noticed is that the kills were more surprising; you'd expect them to die in one way, but they die in another. You will never see them coming. this movie is also somewhat--and thankfully--unpredictable. And if you are a fan of the series, you will probably and most likely like the ending.
Now when it comes to 3-D overall its alright. The best 3-D is probably in the opening credits when things fall through the screen and glass shatters all over.
So, personally, I would give this movie a 4 out of 5 star rating, but professionally a 2 out of 5 star rating. If your a fan of the series or you just like horror movies with not much of a great story, you'll most likely enjoy this film and its originality. If your care about good stories or are easily nauseated, you won't probably like this.