Everyone's promising an R rating these days, even for the shit I didn't ask for, like this, which is also a movie that I don't think anyone asked for. "For adults" The hell? Death Note was never really aimed at adults in the first place, it was aimed at young teens. At the end of the day, it's a story that could easily be told with a PG-13 rating. But then again, we're talking about cramming an entire anime, of which only one half is good, into what will likely be a two hour movie, so I'm not holding my breath on it being good, Rated-R or not.
If Ghost in the Shell promises the same thing that'll be different - since that story is extremely violent and would benefit from the R rating.