Speaking strictly from a J-cinema fan/patriot point of view, "Chatroom" is a cause for celebration. It's set in London, stars some of the brightest young talent in the United Kingdom, centers around the timely topic of social networking — and the whole thing is directed by Japanese horror meister Hideo Nakata (of "Ringu" and "Dark Water" fame)!
The media are calling it "gyaku yunyu" — reverse import product. It happens with such stuff as cars, designer clothes and sake, but much less often with films. A Japanese director working overseas, on a film with not a hint of anything Japanese about it, just doesn't come around very often. And it happens to be Nakata's second such endeavor, after "The Ring Two" in 2005, which fans will remember was a pretty absorbing thriller starring Naomi Watts.
Since then, Nakata left Japan for Hollywood before transplanting himself to London. Rumor has it the director isn't really comfortable with speaking English but he prefers the dark, moody British weather to that in Hollywood and, indeed, deploys the atmospheric London rain (specifically around Camden Lock) to full advantage in "Chatroom."