Ringu 2 for me has to be one of the best sequels made. It has all the feel of Ring and also refers to back to the original movie. The scene at the hospital with the kid from the original who is too frightened to see a TV was a brilliant piece of look back setting.
It is definately a movie that makes one think that Ringu & Ringu 2 were one whole movie split into two separate ones. There is no indication of a budget increase, or special effects to impress existing fans, and definately holds the Ringu style strong.
With clever use of the original cast and elimination of them when needed and the introduction of newer characters makes this film seem as though you have already seen it but are reminded, that you have not.
Yes it is scary, yes it delves more into the mind of Sadako and Yoichi in brilliant technique and yes it will continue your nightmares. I think that something very clever has gone on with the directors in how they want to leave the audience thinking. The original movie left the audience thinking about something coming out of their TV. Then, in the second, tries to create a fear of TV all together and combined with what we see in the original and now in the sequel, does a bloody good job.
I am personally fearful of an "off" TV in a dark room alone. I know nothing is gonna happen, or that Sadako is not real. However, because of the shear impact that this movie has had on me my imagination can create a fear so bad that I must sleep with the TV on.