I am never into Death Note and I came to be interested in it because of the very first movie. I love the battle of the wits between Light and L although I was left a bit duh with Kira killing Shiori at the end of the first movie. I started to lose interest with the second movie as the theme of intelligence gets diluted with the usual cliche of people going crazy, love is driving people mad, and supernatural powers.
Death Note: Light Up the New World is set up 10 years after the original Death Note story takes place. Unfortunately, it is not capable to stand on its own. Not only with the references to the original Death Note story and characters but also with the plot, sub-plots, and tricks: new characters who are basically emulate Light vs L (even with the mention of Light's DNA and L's DNA for their successors), Misa and other characters who can't get over the now dead Light and L, giving up Death Note's ownership to forget about it if interrogated, can't be killed because someone else already writes down the name in the other Death Note, and many more. Perhaps the only original sub-plot is with 6 Death Notes currently present in the human world but that is also not used wisely since Shien (who is thought to be Kira's successor) kills most of them to gather the Death Notes and the story eventually focuses on him vs Ryuzaki (who is L's successor) quite quickly.
For people who are not familiar with the original story, I think they will find the tricks and plots quite smart and interesting, just like how I felt when watching the first Death Note. However, I am not sure if this movie is catered towards them since there are things which are not explained explicitly (e.g shinigami's eyes, Death Note rules) and audience who watch this for the first time may not understand. Even so, if this marketed towards people who is familiar with Death Note to begin with, there is nothing new here to make us feel excited.
When the movie was initially out in the cinema, I was tempted to watch :p But after seeing the reviews, I decided not to watch. Thank goodness I did and thanks SIA for having this in the in flight entertainment.