Since I read this after reading book 3, it made a lot more sense to me than the 18 months between book 2 and 3.
Anyway, I'm glad that Sarah finally made her mind up and chose Michael, he'd always cared for her so for them to end up together has made me happy for them. Team Michael!
As for the rest, everything that had been building up over the previous three books was brought to a head in this and we see the final showdown with the Council and some of the other Vampires. I'm glad a lot of it fell on the good guys side.
If you're going to read this, you should read them as closely together as possible to get the full affect of the story.
I've seen the author is planning on a fifth book, but I think the series has ended well enough without it so I don't think I'll read it if it does come out.