At this point, it would take something incredibly massive to mess up this series.
The Andrews' duo have got a set formula and if you didn't like the first or second book, you're not gonna enjoy the series. It's a little trope-y yet original and the writing is entertaining, and solid. Additionally, it nicely fills my quota for urban fantasy.
More so, I really enjoy Kate as a character. Where Anita Blake ended up tasteless and plain disgusting in the later books, Kate Daniels continues to retain her original personality of bad-assery, even if she always ends up needing to get saved at the end.