While the changes made in adapting the movie from the book were to the benefit of the film, there are still elements of the story in which it is difficult to suspend ones disbelief.
As far as how Safe Haven fits into the Nicholas Sparks film log, it's no Notebook, it is not even as strong as Nights at Rodanthe, but it is better than the worst Sparks' movies, Message in a Bottle and A Walk to Remember. SH is on par with Lucky One. Hot and pretty actors with a mediocre story involving similar plot points make them companion pieces. Not as good as Dear John or the Last Song. Somewhere in the middle of the Sparks Spectrum.
By the by, I submitted what was basically the first two paragraphs posted here to the website that requested my review of the movie. The following message displayed: "Your submission has triggered the spam filter and will not be accepted." Ponder that.