I didn't know there was a sequel to Night Watch. Apparently there is. I'm reading it.
Here's what I'm taking away from it so far:
* The author relies too much on musical allegories -- he puts in song lyrics and then characters comment on them.
* The writing is just as good as the first one.
* I love that the Dark Ones are really just libertarians -- they just want the freedom to do as they wish and let everyone else do as they wish also, while the Light Ones are trying to impose order on chaos.
* I get the feeling that the author has made out the Dark Ones as the "permanent" bad guys even though in one story in Day Watch the Light Ones are actually worse than the Dark Ones. That kind of bugs me a little, but it won't stop me from reading.
* Because the Dark Ones are the bad guys, it was really hard for me to (spoiler) watch Alisa die at the end of the first story after I'd spent so much time getting involved in her character. On the bright side, though, that whole first story was written in a way that it made the ending that much more painful.
Overall, Night Watch and Day Watch are good. You may enjoy them.