I agree, Night Watch is one of his best books. And it's one of his best books BECAUSE of the characterization. We know Sam Vimes by now- what he does, why he does it. His history. If you took the plot of Night Watch, and just substituted a generic watchman, it wouldn't be NEARLY as effective.

And the downside of that is, is that you have to write a lot about a character before he gets characterized well. It's one of the most infuriating things about, well, fiction, to me. In anything serialized- books and TV shows especially- later books/seasons are very often much better than the first one. Because by then, we know the characters, we understand them, and you can tell richer stories by using that as a base.

(Note that it's not always "the later the book/episode, the better." I'm just saying that once you have a base to build on, you can build a stronger story)

Granny Weatherwax, and the witches in general, are another great example of this. In Equal Rites, Granny is pretty bland. Wyrd sisters starts to flesh her out, Witches Abroad adds some motivation to the three witches, but it's really at, say, Lords and Ladies, or Carpe Jugulum, that the characters are fully realized.

So, it's annoying that it takes so long to get awesome characters. But it's great that they do, in the end, become awesome.