New Moon is a tough read. Much more difficult than Twilight was. It is dark, moody, brooding and depressing.
Edward left Bella. She is free of him, for now. This is both good and bad. Good due to the fact that Edward has not been the ideal boyfriend (side note, read my commentary on Twilight, linked below). This is bad since Bella is a mess. In actuality, she is more like an emotional train wreck.
Bella is having a hard time letting go and moving forward with her life, sans Edward. She doesn't want to move onwards and upwards. She acknowledges that the pain she is feeling may lessen with time. Yet, she seems to relish in tormenting herself.
Once you get past that, the book moves at an extraordinarily slow pace. It reminds me of one of those days where everything seems to be moving sluggishly around you.