The point of a "final" book in a series is to wrap things up and give some sort of closure to the readers, who (when it's a good series), will mourn the loss of the characters, and that is exactly what this books does. While is it not the best book in the series (it lacks most of the heart-racing-can't-turn-the-page-fast-enough anticipation), it mostly give the audience what they want, what they have been waiting for since reading the last lines of the previous book, or even since reading the first lines of the first book. I see many reviews lamenting the fact that ultimately Bella did not change much after her "transformation" - in truth, did we want her to change? Did we want to watch her go mad with bloodlust and rip people apart? No. (Stephen King said, upon ending a beloved series, no matter what the author does, some will love it and some will hate it, you just can't please everyone, especially when you are taking away characters they have known and fallen in love with). Meyer has achieved closure on a good series where the characters are held dear (hence the fact that I cannot bear to watch the Twilight movie, as the actors are not as I imagined the characters, and I prefer them the way they are in my head). It is likely that this is not truly "the end", but at least if Midnight Sun does eventually get finished and published, we already know the eventual outcome and will be able to read it a little more calmly.
It should also be said that Meyer's talent for making readers love and care about her characters is readily apparent in The Host, and I will await any new fiction that she produces.